Turing’s Cathedral

On the plane to Ethiopia, and while sweating in my tent at night from the relentless heat at Filoha, I read Turing’s Cathedral, a book my Dad told me I should read. He was right, it’s well worth reading. It’s also timely, as my wife had us watch the movie Deus_ex_Machina for a recent family movie night.

In Deus_ex_Machina, a lone genius constructs an artificial intelligence (AI), which he then subjects to a Turing test to see if she can pass as a conscious being. The movie is thought provoking and disturbing. You can have a brief conversation with the AI, who is named Ava, here. She can even draw a picture of you.

The book Turing’s Cathedral describes the building of one of the first artificial intelligences: the MANIAC computer at Princeton’s Institute for Advanced Studies in the 1940s and 50s. The building of the MANIAC was an intensely collaborative team project. While Hollywood loves isolated mad scientists working in remote lairs, nowadays real scientific advances are usually the result of team effort. No one person can have enough expertise to do everything that needs to be done. AIs that can pass the Turing test will be the result of teamwork on a massive scale.

The book is titled Turing’s Cathedral, but the main character is not Alan Turing (who provided the theoretical foundations for computers), but Johnny von Neumann, who among other things, invented game theory and cellular automata, and played key roles in developing the first atomic weapons and digital computers. Von Neumann was an intensely social genius who built and led the team of people who made the MANIAC, and who traveled extensively, providing intellectual connectivity between Princeton, Los Alamos, Cambridge and other key hives of activity.

The author of Turing’s Cathedral is George Dyson, who grew up at the Institute for Advanced Studies, where his father Freeman Dyson was a fellow. Dyson shows how the development of computers and atomic weapons were intimately linked, and also connected to evolution and genetics. MANIAC’s first job was to run simulations of thermonuclear explosions. Soon after, Nils Aall Barricelli programmed MANIAC to run simulations of evolution.

Evolution, it turns out, is key to thinking about logic, mathematics, and the stuff of thought. One of the central puzzles of mathematics in the early 20th Century was whether all true mathematical statements could be derived from a simple set of axioms. Mathematician David Hilbert argued that “from a strictly limited set of axioms, all mathematical truths could be reached by a sequence of well-defined logical steps.” (Dyson 2012: 49) Bertrand Russell and Alfred North Whitehead tried to do this in Principia Mathematica, which despite covering nearly 2,000 pages “still left fundamental questions unresolved” (Dyson 2012: 49). Von Neumann took on the challenge in 1925 in a paper, “An axiomatization of set theory,” which provided a more concise and more nearly complete answer to the problem. But in 1936, Kurt Gödel published a paper that argued that the project could never be completed, because mathematics was fundamentally incomplete: “within any formal system sufficiently powerful to include ordinary arithmetic, there will always be undecidable statements that cannot be proved true, yet cannot be proved false” (Dyson 2012:50).

This incompleteness of mathematics, and logical systems generally, relates to insight and intuition. Systematic and logical thinking alone can only get you so far. Insights involve leaps, making unexpected connections. Insight is evolutionarily equivalent to mutation: random changes that sometimes result in improvements.

When Turing worked on the Manchester Mark I computer in 1949, he made sure to install a random number generator. This enabled the computer to take advantage of mutations, or “guesses,” and learn from its mistakes.

Intellectual thought, and biological evolution, both depend on two key things: accumulated change, and mutation. Accumulated change ensures that past advances are preserved. Mutation provides the material for new solutions to problems. Most mutations don’t work, but some do. Adding the good mutations to the accumulated wisdom of previous generations permits advances to be made much more rapidly than if everything had to be attempted at once.

During World War II, Turing developed a machine to break the code used in German war communications. The code was too complicated to be solved all at once. But by using a mutating, evolving process, Turing managed to evolve solutions to the problems.

Computers evolve, and DNA is a computer. When Dad told me I needed to read Turing’s Cathedral, he told me, “DNA is a Turing machine!” And he’s right. Dyson doesn’t really develop this point, but he hints at it.

A Turing machine is a universal computer. When Turing proposed the machine in 1936, many people believed that thought was somehow distinct from machines: thoughts are the work of souls, which machines can never have. But Turing proposed that a machine could produce all computable statements. Turing described the machine as having a tape fed into it. The machine can read symbols on the tape, write symbols on the tape, and move the tape left or right. The machine is mindless, but it produces intelligent behavior. Our world today is densely populated with Turing machines running on our computers, phones, and the cloud.

DNA is essentially the tape in a cellular Turing machine. It stores digital information to run the programs that the cell carries out. The cellular mechanisms read the DNA tape, copying portions of it into RNA, which may either be translated into proteins, or used to regulate particular portions of the DNA, or other cellular processes. DNA is mindless, but it acts intelligently. DNA encodes complicated subroutines that involve numerous genes that regulate the production of proteins. But because DNA is digital and universal, in principle it could be used to store any kind of information. Perhaps someday artificial computers will use DNA memories.

For the first few hundred pages, I thought that Turing’s cathedral was the MANIAC computer. But no, as it turns out, the cathedral is Google: that vast conglomeration of Turing machines that knows so much about everyone who has ever searched the Internet. Ava, the AI in Deus_ex_Machina, is created by a man who runs a company, Blue Book, that is a thinly veiled version of Google. Though Ava is created by a lone genius, she learns to understand humans by being granted access to Blue Book searches and cell phone conversations. In this way the AI is created by all of us. And Dyson argues that Google and other online giants, such as Facebook and Amazon, are evolving towards artificial intelligence as they learn from us.

And as computers become more like us, we are increasingly becoming like computers. Reasonably well off people in rich countries have all become cyborgs, and this trend is expanding worldwide. I started becoming a cyborg when Dad gave me an IBM clone computer. This was not my first computer, but it was the first one with a floppy drive (instead of a cassette tape) and enough memory to store what I wrote: papers for classes, college application essays, stories, notes for science fiction worlds, and other personal writings. Soon a substantial portion of what I think of as me was stored on this machine. It didn’t have as much memory as my brain, but it remembered more accurately.

My current laptop retains most of these old memories (though some have been lost through decay, copying errors, failures to store things properly, and loss of compatibility between old files and new programs). But my cyborg existence doesn’t depend on a single machine anymore. Instead it is smeared out across the Cloud: Gmail, Facebook, Dropbox, Snapfish, Google’s memory of my search history, Amazon’s memory of my purchases. The Web may know more about me than I do. With every bit we post, with every search we enter, with every product we buy, we feeding the Web information about human behavior and preferences. We are all building the next AI. And as the Web (or Google or whatever) evolves awareness – well, I hope it is benign.

Works cited:

Dyson, G. (2012). Turing’s Cathedral: The Origins of the Digital Universe, Pantheon.

Down in the Valley

On my last trip to Ethiopia, I visited Guassa, at the top of the Great Rift Valley escarpment. In early August I traveled to Filoha, down towards the bottom of the Great Rift Valley, to visit my graduate student Kristy, who spent the summer working as a volunteer for Larissa Swedell’s hamadryas baboon project.

On the flight from Minnesota to Toronto I sat next to a woman in a black burqa that covered everything but her eyes, hands and feet. Dark henna designs decorated her hands. She spoke in surprisingly Minnesotan English. The number of people who both looked and sounded different from stereotypical Minnesotans increased as I approached the boarding gate for the connecting flight to Toronto. Connecting passengers had to stand in line to get stickers on our boarding passes to board the flight to Addis Ababa (which they spelled differently in Canada: Addis Abeba, and the announcer pronounced differently: “Ad-dees” instead of “Add-iss”). Most of the people in line were Ethiopians, and seemed a generally prosperous group: well fed, many of them tall and confident-looking, with fancy clothes, hair and jewelry. The line was chaotic, long, slow and crowded and midway through I gave up on it and tried to board. No luck; without the sticker I was sent back. So I was one of the last people to board the plane, and had to put my carry-on bag several rows ahead of my seat.

Ethiopia looks, smells, and sounds so different from other places I’ve worked in Africa. The people are diverse, with something like 80 different languages spoken in the country. But in general they look intermediate between sub-Saharan Africans and people of the Middle East. Which makes sense, because Ethiopia is right in between Africa and the Middle East. The national language, Amharic, is closely related to Arabic and Hebrew. Other common languages, like Oromo, are closer to Somali.

On the flight I worked my way through a bit of the Amharic phrasebook I got for my last visit to Ethiopia. The Amharic language uses a writing system that descends from an ancestor of Phoenician, the first alphabet and ancestor of Hebrew, Arabic, Etruscan, Greek and Roman alphabets. It is a syllabary, with 33 sets of symbols, each of which has 7 versions for the vowels eu (pronounced like in French, neuf), u, i, a, eə, and o. This means there are 231 symbols to memorize. Fortunately the symbols in a set change in a sort of regular way depending on which vowel they represent.

Some Amharic letters (from https://en.wikipedia.org/wiki/Amharic)
Some Amharic letters (from https://en.wikipedia.org/wiki/Amharic)

The series for m starts of looking like a pair of spectacles, for meu. For mu, there is a handle on the right side. For mi, there is a long handle on the right side, with a rightward line at the base of the handle, like an old fashioned pair of handheld spectacles. For ma, the rightward line disappears and you just get spectacles with a simple handle. For me, a little circle gets added to the handle. For , the handle shifts over to the left side and gets bent. For mo the handle stays on the left side but straightens up.

Coca-Cola in Amharic
Coca-Cola in Amharic

The Amharic script is beautiful, and having it on everything from road signs to Coke bottles imparts a distinctive feel to the country. We’re not in Kansas anymore.

The distinctiveness of the script stands as a reminder for how rapidly cultural evolution occurs. In general, the symbols look nothing like their distant cousins in other living alphabets. (There are some superficial similarities with the Georgian alphabet, from another remote mountain kingdom, but these are the result of accidental convergence, rather than cultural transmission.) The series for t does look rather like a Roman t, and the series for s looks like a Hebrew sh, but I don’t know if these are shared ancestral features or later convergences.

The variety of Afro-Asiatic languages spoken in Ethiopia suggests that this is an ancient center of diversification for this language family. Given the striking differences in appearance between speakers of Amharic and the peoples across the Red Sea in Arabia, this makes me wonder how much of the phenotypic difference in peoples has evolved in parallel with the language differences. As the proto-Afro-Asiatic people spread from their ancestral homeland, whether this was in Africa or Asia, surely they intermarried with local people along the way, so there would be gene flow as well as within-lineage change in phenotype.

There is a similar variety of appearance in speakers of Indo-European languages, from the pale blondes of Sweden to the brown-skinned, black-haired speakers of various languages of India. We tend to think of cultural evolution as being rapid and biological evolution as slow. But subtle changes, such as pigmentation of hair and skin, can happen fast enough that people who speak languages that are clearly part of the same linguistic family may have evolved look rather different.

People used to assume that language transmission was commonly horizontal, and that people speaking related languages aren’t necessarily genetic relatives. And it is true that anyone can learn any language, and imperial and commercial languages commonly spread across widely divergent social groups. But as Cavalli-Sforza and colleagues have shown, there is often striking convergence between the languages people speak and their genetic similarity. Particularly before the advent of modern transportation and mass migrations, people tended to stay close to home, marry people from nearby and within their own language group. As a result, speakers of related languages are commonly genetically related as well (at least for languages with a long local history, as opposed to recently adopted commercial or imperial languages).

Amharic has a whole set of glottalic consonants, produced with glottal stops (like the “t” sound in “butter” with a Cockney accent). This, combined with a vocabulary that is mostly unrelated to European languages or Swahili, gives it an extremely foreign sound to me. But there are some similarities. Swahili has lots of loan words from Arabic, and many of these words are also similar in Amharic, such as words for higher numbers (thirty, forty, and fifty are thelathini, arobaini, and hamsini in Swahili, and seulassa, arba, and hamsa in Amharic). Because of the Italian occupation of Ethiopia (193x-194x), there are also lots of Italian loan words: bravo, ciao, and machina (car).

Ethiopia smells different in part because of the distinctive spices in the food, especially berbere. On the long flight from Toronto to Addis Ababa, the cabin air smelled strongly of berbere. I had my hopes up for excellent meals of Ethiopian style food. Instead we got rubbery pasta and limp vegetables. The scent of berbere must have emerged just from the clothes and pores of so many spice eaters on the plane.

Historically, Ethiopia was a high mountain kingdom surrounded by deserts. This helped it maintain its independence and distinctiveness from surrounding countries and would-be invaders. The Ethiopian Orthodox Church has endured for some 1,500 years or more when most of the surrounding peoples converted to Islam. The distinctive round Ethiopian churches help make this country seem so different from, say, Tanzania, where both Islam and Christianity are more recent arrivals. (The coast of Tanzania has long been Islamic but its history in the interior is more recent.)

Addis Ababa International Airport

 

 

 

 

Stepping off the plane in Ethiopia from the humid warmth of Minnesota was a shock. Addis is high in the mountains and cool. I felt rather cold in my sandals and short sleeves.

The whole arrivals and customs area has been renovated since my visit three years ago, thanks to Chinese money for an entire airport renovation. Immigration was slow and chaotic, but generally hassle-free. People standing at the entrance area checked passports for visas and sent you to the line if you needed to get a visa. The visa line required several steps: first you get the visa, which they fill out by hand in Amharic, then you stand in another line to pay for the visa ($50 now, up from $20 three years ago), and then you stand in another line where they check that you have the visa and paid for it. I found myself standing in line next to the woman in the black burqa who had been on the flight from Minneapolis. She seemed just as confused by everything as I was.

I got $100 worth of Ethiopian birr from an ATM in the baggage claim area. The machine spit out a brick of crisp new bills, more than 2100 birr in 100s, 50s, 10s, 5s and 1s. I couldn’t fold my wallet with all those birr so put them in my travel pouch.

Outside the baggage claim stood a crowd of people welcoming the new arrivals, including family, friends, and hotel and tourist staff. Someone asked me if I was from Egypt. Ethiopia is one of the few places where I’ve mistaken for a Middle Easterner. Later someone asked if I was from Saudi Arabia.

Outside in the parking area I soon found my driver. He introduced himself as Ermias, “which is Jeremiah in the Bible in our language.” I recognized the car as the same one I took to Guassa three years ago. Only then did I remember that this car had broken down for about an hour on the road to Guassa. When I got into the car and rolled down the window, the round, spinning end of the handle came off in my hand.

We drove down the broken, potholed streets of Addis to the house of the tour operator, so I could pay for the trip to Filoha. Outside the gates, sheep foraged in the grass.

Sheep grazing in Addis Ababa
Sheep grazing in Addis Ababa

 

 

 

 

 

 

It was Sunday morning, many people were in church and few cars were on the street. The rough streets ensured that the going was slow even without much traffic. But there were signs of new construction everywhere. Many new buildings enclosed in flimsy looking wooden scaffolding.

New construction in Addis
New construction in Addis

 

 

 

 

 

 

 

 

When Ermias stopped to change money, I bought a liter of cold water to drink along the way. We stopped for gas at what seemed to be a BP station (green signs, but in Amharic letters). The station was off to the side of the road and downhill a bit, with loose gravel and dirt covering the connection to the road. It seemed as if someone had dropped the gas station here by accident. Huge trucks competed for space in the queue with tiny cars. Payment seemed entirely cash and directly to the attendant at each pump.

Last time we drove up, up, up to Guassa, up to the crest of the rift escarpment. This time we drove down, down, down to Filoha, down towards the bottom of the rift. According to my GPS, one gas station in Addis Ababa is at 2,219 m (7,323 feet), Darjeeling Cliff at Guassa is 3,383 m (11,164 feet), and Filoha is 728 m (2,402 feet) above sea level. Filoha is thus similar in elevation to Gombe, which my GPS says is 774 m (2,554 feet) at the mouth of Rutanga Stream. The rift valley goes lower, eventually dropping well below sea level in the Danakil Depression, where the Awash River flows into a dry dusty pan and disappears.

We took the new expressway (built by the Chinese), which ran parallel to the new railroad (also Chinese built), which both link Addis to Djibouti, the closest seaport (now that Eritrea has become independent, depriving Ethiopia of a direct connection to the coast). The expressway is a dual carriageway toll road with six lanes of traffic, which contributed to the feeling of not being in Africa at all.

Close to Addis the countryside is well watered with expansive fields of green. Further down into the rift we saw more signs of geological activity: vast fields of black lava rock interspersed with green grass and isolated trees. The further down we went the more marabou storks and vultures appeared by the side of the road.

I tried to stay awake to enjoy the whole ride but was too sleep deprived and drifted in and out of consciousness. We left the freeway to a join a road that was narrow but still freshly paved and smooth. More Chinese roadwork, I’m sure.

The Chinese are playing a role in Ethiopia – and much of the rest of Africa – similar to what the British played throughout much of the world in the 19th Century, and the Americans in the 20th Century. I suppose the British nowadays are too busy with finance, and the Americans are too busy developing new apps for the iPhone, to bother with such concrete things as roads, buildings and railways in Africa.

We passed a truckload of camels, packed together sitting down with their necks upright. Ermias said they were going to Saudi Arabia.

Metahora Church stack of tyresWe stopped for lunch at Metehara, the last major town before Filoha. We parked in front of a small restaurant. On a raised area at the front of the restaurant, a woman knelt before a set of coffee cups, preparing coffee in the bunna ceremony. A charcoal burner held three sticks of burning incense. Ermias explained that they only had fasting food, meaning vegetarian items, because of the religious holiday.

“Which holiday is it?”

“Something from the Bible.”

Goat and tricycle car in Metehara
Goat and tricycle car in Metehara

 

 

 

 

 

 

Ermias ordered something for me that turned out to be a huge round platter with a huge round flat piece of spongy enjera bread with little piles of tasty vegetarian delights. After lunch Ermias changed the flat rear tire of his car. His skin glistened with sweat after just a few minutes work. It was getting hot down here.

We soon reached the park gate of Amhara National Park. This is the major national park in southern Ethiopia. We drove off the paved road to the little building by the simple gate, where a sign explained the rules and fees.

Awash National Park gate
Awash National Park gate

Most of the tourist facilities are to the south, along the Awash River, but we would be going to the very northern end of the park, 32 km away. I paid my park entrance fee, plus an additional 150 birr ($7) for an armed guard to accompany us to Filoha. The risk of banditry makes armed guards a necessary requirement for travelers in the park.

We drove back across the paved highway onto the gravel road leading north. The gravel road suddenly jogged sharply to the right, to make its way around the new Chinese-built railroad that cut directly across the park. This must be a huge barrier to wildlife in the park now, as the tracks travel between deep drainage ditches dug on either side.

We drove slowly down the hot, dusty, winding gravel and dirt road. A low thicket of Acacia trees extended in all directions from either side of the road, with some distant hills and mountains visible. From time to time, birds flew out in brilliant flashes of color. These were birds familiar to me from when I habituated baboons in Kenya, and from visits to other dry parts of East Africa: White Headed Buffalo Weavers, Bee Eaters, Malachite Kingfishers, Lilac Breasted Rollers, glossy Longtailed Starlings. In America, Starlings are kind of dull, mottled brownish black nuisance birds. In Africa, Starlings are glorious birds with iridescent plumage and brilliant colors. I felt an intense sense of homecoming seeing the familiar birds and trees of the Acacia woodland. From time to time a dik-dik, a tiny little fairy of an antelope, bounded away in the bushes. A lesser kudu crossed the road, a beautiful striped antelope with long spiral horns.

On the highway, the wind roaring past the open windows kept us cool. On the slow gravel road, the sun baked the slow moving car, and the air provided no relief. I kept thinking that we were pretty remote now, we were about to get to camp, but then we would keep driving for ages more. A set of rounded white structures showed in the distance, looking like a set of tents. That must be camp! But as we got closer, it became clear that these were simple huts of sticks covered in tattered white sheeting.

“An Afar camp,” Ermias explained. “Pastoralist people.”

Soon after we passed a group of Afar herders on the road: people with very dark skin, wearing bright white cloths draped over the shoulder and wrapped around the waist. The Afar people are the namesakes of the taxonomic name of Lucy, the famous fossil found not too far from here: Australopithecus afarensis. They herd cattle, goats and camels. They speak a Cushitic language related to Somali. Technically they are not supposed to be in the National Park but thousands of them live in Awash and keep their herds here.

The road went on and on and on. The heat grew increasingly oven-like. The landscape grew monotonous and in my sleep-deprived state I faded in and out of awareness. The water in my bottle became as hot as tea.

We passed through blasted landscapes of lava rock, down steep gullies, and passed mysterious peaked mounds of rock (built by Italians during the war, and said to cover bombs). Then, after an hour or more of Acacia scrub, stands of Doum palms appeared along the side of the road, at the edges of wetlands that flooded the road itself. We drove through water and mud. A craggy wall of lava appeared to the left. To the right, the peaked roofs of huts appeared.

He parked the car by one of the huts in what appeared to be an empty, quiet camp.

“They know you are coming?” Eremias asked.

“Yes, they know I am coming.”

Soon two women appeared, smiling and walking down the hill towards us from another pair of huts: Alex, who is doing her dissertation research here, and Kristy, looking red from the sun and very much at home in Filoha.

I asked Ermias to take a picture of us.

“Okay, now we have evidence of my visit.”

“Right, so now you can leave?” joked Ermias.

Alex, Kristy and Mike at the Filoha camp.
Alex, Kristy and Mike at the Filoha camp.

Kyoto Mountaineering Club

In July, I attended the 30th Annual Meeting of the Japan Primate Society, and the meetings of the Primate and Wildlife Society. This year is the 50th anniversary of research at Mahale Mountains, the 55th anniversary of research at Gombe.

Japanese primatology started in 1948, with a trip by Kinji Imanishi to Koshima Island, where he intended to study feral horses but ended up studying Japanese monkeys instead.

Starting in the 1950s, Japanese primatologists embarked on expeditions into remote areas of Africa to study gorillas, chimpanzees, and bonobos. They founded long-term research sites and documented the behavior and ecology of African apes.

Professor Tetsuro Matsuzawa talked about his years in the Mountaineering Club at Kyoto University. He used the club as a way to recruit potential field workers: people who liked being outdoors, who weren’t afraid of physical challenges, people with a pioneering spirit.

Matsuzawa and other speakers showed slides of the early days of Japanese primatology in Africa: teams of tough, wiry-looking men ready to endure hardship for the sake of knowledge. Matsuzawa noted that in the Primate and Wildlife Sciences program, of the 21 students, the majority of the students were female, and most students were from countries other than Japan. The “foreign ladies” are willing to undergo the risks and hardships of fieldwork, whereas so few Japanese men are willing to do this that he called them a “critically endangered species.”

Why are so few Japanese men interested in doing primate fieldwork? I suspect that in this respect, Japanese men are the vanguard of a more general problem, not limited to men, or to any particular country. It is my impression that as life has become more comfortable, and communications technology has improved, it has become more difficult for young people to undertake long stretches of time in remote areas with limited electricity, email and Internet access.

This question brought to mind one possible solution to the Fermi Paradox.

Enrico Fermi, a physicist and one of the key scientists on the Manhattan Project, raised this question: given that intelligent life evolved at least once (here on Earth), intelligent life should have evolved on other planets in other star systems as well. And yet we don’t see any evidence of intelligent life elsewhere in the universe. As far as we know, we haven’t been visited by space aliens.

(Though in response to Fermi’s question, Leo Szilard answered “They are among us,” – he said, – “but they call themselves Hungarians.” John von Neumann and several other key scientists working on the Manhattan Project were Hungarian immigrants, and were of such exceptional intelligence that they were jokingly suspected of being extraterrestrials.)

If intelligent life can evolve at least once (as we know it has on Earth), then intelligent life should be able to evolve multiple times. In a galaxy with hundreds of millions of stars, even extremely rare events should occur repeatedly, provided they are possible. And we know that intelligent life forms can do things that make their presence known across interstellar space; we have done this by broadcasting television and radio signals. So if intelligent life has evolved somewhere in our not too distant neighborhood, we should see some evidence of it. And yet we don’t see any such evidence.

When Fermi first proposed his paradox, astronomers had no evidence of planets orbiting other stars. We didn’t know whether planets were rare or common, and whether planets like ours (small and rocky rather than big and gassy, not too close to the sun and not too far from it) were common or rare. Now, thanks to the Kepler planetary search program, astronomers have located thousands of planets around other stars. It looks like nearly every star has at least one planet, and many stars have multiple planets.

Carl Sagan worried that one explanation for the Fermi paradox was that advanced civilizations regularly self-destruct. They learn how to unleash nuclear energy, for example, and destroy their civilizations in nuclear war.

As a college student reading William Gibson’s cyberpunk novels in the 1980s, I wondered whether the explanation might not be nuclear war, but virtual reality. Any sufficiently advanced civilization should develop the tools to simulate reality (as our own society seemed on the verge of doing). Perhaps once virtual realities get good enough, they become so fascinating and absorbing that no one bothers with physical realities any more. Maybe the space aliens aren’t visiting other worlds because they have completely disappeared into their own virtual worlds and simply aren’t interested in anything outside of that?

Virtual reality came into being faster than I imagined it would. It turns out you don’t need high-resolution video plugged into your optic nerves to achieve a sufficiently distracting simulation of reality. Social media, Wi-Fi and smart phones have enabled us to create virtual worlds that become completely absorbing, even though they are mainly text and still images.

Field primatology is much less demanding than interstellar travel. But it requires a pioneering spirit, a willingness to go far from the herd, leave the hive mind, and endure physical challenges: hunger, thirst, sun, rain, insect bites, long days of hiking, and no cell phone connectivity.

Life in rich places like Japan, the US and Europe makes us increasingly ill-adapted for fieldwork. We expect three full meals per day, with frequent snacking opportunities. We expect clean toilets and hot showers. We expect air temperature to be kept within a narrow window: not too hot, not too cold. We expect comfort, personal space and privacy. We expect a life of leisure, depending on machines for much of our transportation.

Giving up these comforts to do fieldwork is challenging. But psychologically, leaving the hive mind may be even more difficult for people who have grown up connected.

When I first went to Kenya to study baboons in 1992, there was no Internet, no email, no cell phones, no faxes. The only way to communicate with folks back home was by mail, which was slow, or by telephone, which was expensive and rarely possible (the nearest pay phone was 40 km from my field site). My little sister tells me that during a long gap between letters from me, my family watched a nature documentary about African wildlife. When a baboon on the show yawned, showing off its long canine teeth, Mom started crying. She had all sorts of worries for me in Africa, but hadn’t thought to worry about baboons until she saw their teeth.

It was hard to be so far away from everyone back home, with so little communication. But for people who grew up plugged in, the prospect of being away from Facebook, Twitter, email and all the rest for months at a time may simply be too horrifying to contemplate.

Whether we have enough people to keep field primatology going is, in the grand scheme of things, a small problem. But it relates to a more general problem: decreasing interest in spending any time outside, away from the comforts of home. When I was growing up, I spent a lot of time vegetating in front of the TV, or reading books in my room. But I also spent a lot of time outside: climbing trees, playing with friends, riding my bike further and further from home, exploring our little town and its parks and the surrounding countryside. Kids these days don’t seem to do quite as much of that. The Internet and social media are so absorbing that there hardly seems any need to go outside.

In many ways, Japan feels like the future. Not a dystopic Bladerunner, cyberpunk or Hunger Games future, and not quite utopia either, but a future imagined by someone with an eye on current trends and a generally optimistic disposition. It is crowded, yet clean and orderly. People live long lives and have few children, resulting in an aging and shrinking population. And perhaps as a result, society overall is a bit less dynamic, a bit more conservative, a bit less risk-tolerant.

Japan is a densely populated country. On the train from Tokyo to Kyoto, the urban sprawl seems nearly continuous, with only scattered rice fields and green, forested mountains rising above the densely packed houses, shopping centers and factories. It seems as if every flat bit of land is settled. Even the forested mountains are, to a large extent, a human modified landscape, being covered mainly by plantations of cedar and other trees, rather than natural forests.

Perhaps as Japan’s population declines, nature will reclaim some land now covered in towns, cities and farms. Forest cover is increasing in North America and Europe, and species like wolves are returning to parts of their former range, like France. Nature has taken back parts of declining cities like Detroit.

The planet needs wild places. If large animals like elephants, lions, wolves and chimpanzees are going to survive, they need open space and natural areas. But if people don’t go outside, and don’t go exploring into natural areas, hunting and fishing and hiking and camping, then who will care if those natural areas are converted to other uses: cleared of timber, planted in crops, dug out for mines, covered in strip malls and parking lots?

Despite such worries, though, I’ve met many young people eager to do fieldwork and embrace the challenges of life away from comforts and the hive mind. And perhaps as the world becomes more wired, connectivity will no longer be an issue, even at the remotest sites. (I’m posting this from Gombe, where the research offices have WiFi.) But it seems wise to ensure the continuation of groups like the Kyoto Mountaineering Club, to encourage people with a pioneering spirit.

Words and Genes

This weekend,  people in the United States set off numerous explosive devices to celebrate 239 years of independence from the United Kingdom. Since this separation, the versions of English spoken in the US and the UK have diverged considerably, but still remain (mostly) intelligible. In contrast, North and South Korea, which have only been separated for 70 years, have been more strictly isolated from one another, and as a result the versions of Korean spoken in the two countries have diverged dramatically:

differences [of mutual unintelligibility] now extend to one third of the words spoken on the streets of Seoul and Pyongyang, and up to two thirds in business and official settings.

A friend of mine who is an actual linguist drew my attention to an app that designed to translate between North and South Korean— an acute problem from people who have defected from North to South.

As Darwin and many others have noted, and as I’ve written about here, such language change bears many striking similarities with biological evolution. These similarities are interesting in their own right, and may be helpful for thinking about the long-running debate in evolutionary biology about whether natural selection acts mainly on genes, individuals, or groups.

A language, like English, or German, or French, is like a biological species. Both languages and species are made up of populations of individuals. Languages and species both have boundaries. In biology, the boundary is sex: a species is defined as a population of individuals that naturally mate and produce fertile offspring with one another. This concept is a pretty good rule of thumb, but turns out to be violated frequently in nature. Oak trees are notoriously promiscuous with oak trees from other species. Of course they mate simply by wafting their sperm into the air (tucked inside pollen grains) so they aren’t the choosiest of breeders. But even among mammals, hybrids frequently occur in nature.

In languages, the boundary is not sex but mutual intelligibility. French is considered a different language from English because, as Steve Martin says, “those French have a different word for everything!” But just as with the biological species concept, this is a useful rule of thumb, rather than an absolute rule. Speakers of closely related languages, like Danish and Swedish, can learn to understand one another with some ease.

Species have subspecies, and languages have dialects. Both are closely related to geography and geographic isolation. Languages like English and Chinese contain “dialects” that may be as mutually unintelligible as pairs of “proper” languages. Because the distinction between a language and a dialect is to some extent political, a common saying among linguists is “A language is a dialect with an army and a navy.”

Similarly, the distinction between species and subspecies in biology is somewhat arbitrary. Baboons, for example, are a widespread group of monkeys, occurring through most of Africa, with one species (Hamadryas baboons) extending their range across the Red Sea into Saudi Arabia and Yemen. Even though baboons are among the most intensively studied nonhuman primates, no one seems to about how many different baboon species there are, and what they should be called. Some people consider all baboons to be subspecies of Papio hamadryas. Other people distinguish ten or more species: Guinea baboon, Hamadryas baboon, Hauglin’s baboon, Anubis baboon, “typical” yellow baboons, Ibean yellow baboon, Kinda baboon, grey-footed baboon, Transvaal chacma baboon, and Cape & desert chacma baboon.

Jolly, C. J. (2001). A proper study for mankind: Analogies from the papionin monkeys and their implications for human evolution. Yearbook of Physical Anthropology, Vol 44. C. Ruff. New York, Wiley-Liss, Inc. 44: 177-204.
Jolly, C. J. (2001). A proper study for mankind: Analogies from the papionin monkeys and their implications for human evolution. Yearbook of Physical Anthropology, Vol 44. C. Ruff. New York, Wiley-Liss, Inc. 44: 177-204.

Interbreeding occurs among all these different kinds of baboons where their ranges overlap, so from the point of view of the traditional biological species concept, they are different species. But calling them all subspecies of Papio hamadryas seems odd because Hamadryas baboons are the most distinctive baboons of all: the males have showy capes and tufted tails, and their societies have an unusual multi-level structure quite different from the usual troops of “savanna baboons.” Moreover, as more studies are conducted of other baboons, it has become clear that each of these species (or subspecies) differs from others. For example, Guinea baboons turn out to have a social system quite similar to that of Hamadryas baboons.

So languages are similar to species, and dialects are similar to subspecies. These categories refer to populations. Within populations, individuals vary greatly, both in their language use and in their genes.

Each individual speaker of a language has her own set of words and rules: an idiolect. My idiolect may be very similar to yours, or quite different, depending on our shared vocabulary, which may include technical terms specific to our work, and idiosyncratic speech habits (which my wife complains I have in abundance).

An idiolect is similar to an individual’s genome. Each individual is unique, but at the same time, each individual speaker of a language shares a broad set of words and rules with other speakers of that language (otherwise they wouldn’t be able to communicate – and wouldn’t be considered speakers of the same language).

Continuing the analogy down to the next level, words are similar to genes. Words and genes are both combinatorial, in that they consist of sequences of smaller units combined to make larger units: syllables and letters in words, codons and nucleotides in genes.

Words are made up of syllables. Some words are made of single syllabus, such as “dog,” “cat,” and “fish.” Longer words can be made by combining syllables: “dogfish,” “catfish.”

Similarly, genes are made up of a series of codons. Unlike syllables, which can be spelled with anywhere from one to six or more letters (“a,” “-ed”, “-ing”, “ouch,” “queue,” “smooch,”), codons are always spelled with three letters.

Spelling is easier in genetics than in linguistics, because while languages may use dozens of letters (e.g., 26 in English), all genes are spelled with only 4 letters: G, A, T, and C. These letters stand for the nucleotides Guanine, Adenine, Thymine, and Cytosine.

Words are generally much shorter than genes, however, Words usually have only a few syllables, whereas genes can contain hundreds or thousands of codons.

Each 3-letter codon is translated into an amino acid; these amino acids are in turn connected up together like cars in a train to make proteins. The whole business of making proteins is very complicated, and is perhaps roughly analogous with the translation of mental representations of words into physical phenomena, such as sounds produced by the vocal tract, or signs made with the hands in sign language, or words written on a page or typed on a screen.

Linguistics Genetics
Combinatorial level Example Example Combinatorial level
Letter A, B, C, D, E, F, G… A, C, G, T Nucleotide
Syllable Dog, cat, in-, un-,-ness CAT, TAG, DAT, DCG Codon
Word Dog, cat, catness, undoglike hemoglobin, melanin, lactase, amylase Gene
Idiolect My particular speech My particular genes Genome
Dialect Upper Midwest American English Homo sapiens sapiens Subspecies
Language English Homo sapiens Species
Family Germanic, Indo-european Hominins, Primates Clade

In addition to being combinatorial, words and genes resemble one another in that they are both products of descent with modification. This is the phrase that Darwin preferred to “evolution,” and is really more precise about what happens in evolution. The descent part means that words and genes both have histories and family trees. The modification part means that both words and genes gradually change over time, across generations.

Both words and genes can undergo small changes, “mutations,” in how they are spelled. Genes can change by as little as one nucleotide. Many such mutations are “silent,” that is, they don’t affect the amino acid sequence made by the gene, because the genetic code is redundant: there are only 20 amino acids, but 64 possible codons. So some amino acids can be spelled several different ways. The amino acid serine, for example, can be spelled TCA, TCC, TCG, or TCT.

Mutations can have a wide range of effects, from not changing gene function at all, to wrecking the gene entirely. Some mutations result in slight improvements.

Words also undergo mutations. Talking about mutations in words is a little tricky in that the letters we use to spell them have an imprecise relationship to the way they are actually pronounced. In linguistics, the actual speech sounds that make up words are called phones.

Thus, “water” is spelled the same way in Dutch and English, but is pronounced slightly differently. Even within English, “water” is pronounced differently by different speakers and dialects. In the American Midwest, “water” is pronounced something like “wah-dur,” whereas in some dialects in England it is pronounced more like “wah-tuh.”

But both words and genes are robust to these small changes. They still work when altered just a little bit – which allows them to evolve.

Words and genes both accumulate small changes over time. These changes tend to cluster geographically. People who live near one another for many generations tend to speak the same language and dialect, and also tend to have more similar genes than people who live further away.

So what does all this have to do with the argument in biology about levels of selection?

In 1976, Richard Dawkins drew attention to the gene’s eye view of biology with his book, The Selfish Gene. Prior to this book, a widespread view in biology was that genes are something organisms use to accomplish certain goals. The heart pumps blood, the kidneys filter blood, and the genes store information and transmit it to the next generation. Dawkins, popularizing work by G. C. Williams and W. D. Hamilton and others, turned this view on its head: organisms are “survival machines” that genes use to make more copies of themselves. Dawkins argued that genes are ruthlessly selfish, because only those genes that succeed in getting copied are transmitted to the next generation.

Many people have objected to this view of evolution. Stephen Jay Gould, for example, argued that natural selection acts on individuals, rather than genes. Biologists including Edward. O. Wilson and David Sloan Wilson have argued that selection acts on multiple levels: genes, individuals, groups, perhaps even species. The debate continues with passionate advocates on each side.

In some ways, I think the debate is entirely sterile. Many people on both sides of the debate seem willing to agree that group selection is mathematically equivalent to kin selection. What really seems to feed the passion in this debate is the connotations that people have towards the idea of genes as “selfish” entities. Many people seem to have the impression that group selection is somehow kinder, gentler, and politically more left-leaning than gene-level selection. This view puzzles me, since plausible mechanisms of group selection are often quite nasty, such as intergroup hostility and warfare.

Genes are exotic entities, only recently discovered, and not fully understood even by professional biologists. Words, however, are familiar things that we all use all the time. So linguistic evolution might be easier to grasp for many of us than genetic evolution.

From a Darwinian perspective, a word is selfish in exactly the same way that a gene is. In both cases, versions that succeed in making more copies of themselves are the ones that persist over time.

Genes get themselves copied through reproduction. In species with sexual reproduction, they depend on their host finding a mate and (if there is any parental care) successfully rearing the resulting offspring.

Words get themselves copied in various ways. Vertical transmission is like biological reproduction, in that words are passed down from parent to child. Words differ from genes in that they are also easily passed among unrelated individuals: horizontal transmission. Horizontal transmission of genes does occur, especially in bacteria, but it is less common in complex multicellular creatures like ourselves.

Words vary among speakers, just as genes vary among individuals. Common words are shared by nearly every member of a language community, but there is still variation, among regions, social groups, interest groups, and individuals.

My idiolect, like my genome, is an ephemeral collection of words and rules. It will vanish when I die (apart from whatever words I have left behind in books and such – but even those will represent only a fraction of my actual idiolect, and will show the influence of co-authors, editors and such). My genome will also vanish when I die (parts of it will live on in my children, but all mixed up with my wife’s genes).

Words, however, have longer histories – as do genes. The word I use for H2O, “water,” comes from ancient roots. We see its cousins in words such as “Wasser” in German and the more distant cousin “voda” in Russian (whence the word “vodka,” “my dear little water”), and “uisge” in Scottish Gaelic (and its distilled descendant word in English, “whiskey”).

In language evolution, selection occurs mainly at the level of words. It is individual words that accumulate changes in their sounds and meanings. Words exist in a constant competition with other words for space in each individual’s vocabulary. Words come and go, depending on fashion, technology, and random drift.

The analogy is of course far from perfect and shouldn’t be pushed too far.

In fact, some linguists don’t like this analogy at all. In a 2014 blog post, linguist Asya Pereltsvaig complains:

words are not “just like genes” in that they are easily borrowed from language to language, even across family boundaries, are subject to conscious choice, and are not subject to natural selection.

The first point is true – sort of. The sort of genetic transmission that we are most familiar with is vertical (parent to offspring) rather than horizontal (from one unrelated individual to another). However, horizontal gene transfer turns out to be more important the people used to think.

Bacteria swap genes fairly frequently, such as when they share genes for resistance to antibiotics (like Deadheads swapping tapes of old Grateful Dead shows).

And according to one recent study, some 8% of the human genome originated in retroviruses.

So actually words and genes quite similar in this respect. Most genes, and most words, come from your parents, but some genes and words come from elsewhere, sometimes even quite unrelated sources.

The other claim, that words are not “subject to natural selection,” is also debatable. Pereltsvaig focuses attention the fact that word form is arbitrary.

As was noted by the “father of modern linguistics” Ferdinand de Saussure, the association of sound and meaning of a word is largely random: the sound of house is neither more appropriate to the concept nor better for the “survival of the fittest” than maison (French), dom (Russian), bayit (Hebrew), or iglu (Inuktitut)

It is true that the particular form of a word is basically arbitrary. But it is not true that selection has nothing to do with word form. Over time, long words that are frequently used get shortened. In both French and English, the invention of two-wheeled human-powered transportation required an accompanying new word (“vélocipède,” bicycle), which was subsequently shortened in both languages (“vélo,” bike). French teenagers commonly use “gar” for boy instead of the longer “garçon.” Words that are hard for native speakers to pronounce get changed to make pronunciation easier. Words whose meanings are transparently obvious to native speakers may generally catch on better than words whose meaning is opaque. For example, the term “earworm” (to describe a catchy tune that gets stuck in your ear) has a better chance of being understood, used, and catching on among English speakers than the original German word that it is translated from, “Ohrwurm“.

Pereltsvaig also claims, “words provide no adaptive advantage to people(s) who have them.”

But I disagree with this as well. Words are crucial to survival and reproductive success in human societies. Someone unable to use words at all would have tremendous difficulty holding a job or finding a mate. Using words well is essential, not just for those who write for a living, but also for anyone who talks with other people.

In some cases, correct understanding of a word could make the difference between life and death. One time at Gombe, an American colleague of mine thought she saw a hippo swimming in Lake Tanganyika. She grew alarmed, as several people were swimming nearby. Hippos may seem harmless but they enormous, terrifying beasts with huge sharp tusks (usually hidden inside their vast mouths). Hippos are often said to kill more people in Africa each year than crocodiles. To warn the swimmers, she shouted “Kifaru! Kifaru!” The Swahili-speaking swimmers just looked at her with a puzzled expression – since kifaru means rhinoceros in Swahili, and there was no risk whatsoever that there would be a rhino in the water. It turned out there wasn’t a kiboko (hippo) either, but if there had been, this linguistic mistake could have proved deadly.

The particular words we use tell others about our social status, our level of education, our sense of humor and style, and many other aspects that directly affect our reproductive success. Blurting out the wrong set of words can cost a person dearly (see, for example, James Watson, Tim Hunt, Donald Trump).

Looking at evolution from a gene’s eye view provides insights that simply aren’t available from other perspectives. Many aspects of biology don’t make any sense at all except from a gene’s eye view. The very existence of sex, for example. If selection occurred at the level of individuals, we should see individuals mainly making exact copies of themselves (clones). This sometimes happens in plants and animals, and is the norm for bacteria, but the widespread occurrence of sexual production is very difficult to explain, unless evolution is mainly about the replication of genes.

At the same time, words and genes both exist within incredibly complex systems in which the influence of any one word or gene may not be obvious. Just as each word contributes a tiny bit to each individual’s language output, each gene contributes a bit to each individual’s biological output. The total number of words that an individual speaker knows is estimated to be around 20,000 – 35,000. Coincidentally, this happens to be quite similar to the number of protein-coding genes in the human genome (around 20,000-25,000). Thus, in most cases, any single word or gene is likely to have only a small and subtle influence on an individual’s survival and reproductive success.

Words combine in complex ways to produce phrases, sentences, and longer things like poems, songs, articles and books. Gene products interact in complicated ways to produce living bodies and regulate the expression of other genes.

Both words and genes only make sense within the context of the complex system in which they exist. The French word “entrée” means something eaten at the start of a meal in French (the “entry” into the meal). When English speakers borrowed this word, they rather confusingly used it to refer to the main course of a meal. Similarly, the “meaning” of genes depends on the context in which the genes occur. In animals with red blood cells, the genes for hemoglobin make proteins that carry oxygen. But what would happen if these genes were inserted into a bloodless organism, such as a bacterium? Probably just an accumulation of protein that has no use whatsoever for the bacterium. (This may seem like a weirdly pointless experiment, but it has actually been done to produce and and study mammoth hemoglobin).

Additionally, just because words and genes are both “selfish,” in the sense that those that are better at getting copied are the ones that become most common in a given population, does not mean that they have to promote behavior that is selfish. Animals engage in all sorts of altruistic behavior, much of which is presumably the result of genes promoting altruism – that is in fact the central topic of The Selfish Gene.

For example, individual words might be “selfish,” in the sense that words with features that promote being copied get copied more often. But the words themselves don’t necessarily promote selfish behavior. For example, “Do unto others as you would have done unto you” is a combination of words that has been extremely successful in getting itself copied. Perhaps the great majority of the hundreds of millions of people who speak English have some version of this phrase stored in their memories; and other languages transmit equivalent versions of this phrase. The phrase is good at getting copied, but it advocates cooperative behavior, rather than selfish behavior. This is precisely why the phrase has been so successful. People who make an effort to follow the idea encoded in this phrase are likely more successful at navigating the complexities of village and urban life than people who are mean-spirited and selfish. “Selfish” words, like “selfish” genes, often promote cooperative behavior.

Language evolution and biological evolution both result from the accumulation of small changes at fundamental levels: words and genes. Words are “selfish” in exactly the same way as genes. Words and genes that have attributes that increase their likelihood of being reproduced become more common in the population. But neither words nor genes have goals, or minds, or emotions, or feelings of being selfish, altruistic, or anything else. They are just bits of information that happen to exist within copying systems. And just because these bits of information can be described as selfish doesn’t mean that they invariably code for selfish behavior.

 

Chimpanzee Violence and the Post-War Dream

Below is the text (more or less) from the TEDxUMN talk that I gave on 03 May 2015. A video of the talk is here.

I grew up in the Cold War.

The books, movies, and music were filled with fears of the end of the world.

One of my favorite albums was Pink Floyd’s The Final Cut: A Requiem for the Post-War Dream.

The album ended with the song: Two Suns in the Sunset.

The second sun being, of course, a thermonuclear explosion.

Looks like the human race is run.

War seemed inevitable. There was no way out.

But despite all the doom and gloom, it turned out these were actually the final years of the Cold War.

In 1989, the Berlin wall fell, and in 1991 the Soviet Union collapsed, not with a bang, but with a whimper.

St. Basil's Cathedral, Moscow. (August 1991)
St. Basil’s Cathedral, Moscow. (August 1991)

 

 

 

 

 

 

 

 

I was lucky enough to get a glimpse behind the Iron Curtain just as it was coming down.

I had a fellowship to study in England that came with money for summer travel in Europe.

I used that money to travel to Russia, then all the way to China on the Tran-Siberian Railroad. It turns out that this was the last summer that the Soviet Union existed.

And on the other side of Iron Curtain I found that people were pretty much just like us.

Soviet soldiers near Red Square, Moscow. (August 1991)
Soviet soldiers near Red Square, Moscow. (August 1991)

 

 

 

 

 

 

Walking around Moscow near Red Square, I saw Soviet soldiers – boys, really, about my age – playing around in a children’s park, taking pictures of each other.

This was an exciting time, with the Soviet Bloc and China opening up to the outside world.

It gave me hope that maybe war was something we can overcome.

I grew up worried about war but fascinated by apes.

http://eden.uktv.co.uk/gorilla-revisted-david-attenborough/gallery/photos-gorilla-revisted-david-attenborough/#4
http://eden.uktv.co.uk/gorilla-revisted-david-attenborough/gallery/photos-gorilla-revisted-david-attenborough/#4

 

 

 

 

 

 

As a kid, I saw Dian Fossey on TV with mountain gorillas and thought to myself: that’s what I want to be when I grow up.

It’s because of war, though, that I don’t study gorillas.

The mountain gorilla study is located in Rwanda, a tiny country in the heart of Africa. After college, when I wrote to the directors of the gorilla study asking if they needed research assistants, they wrote back saying they were closing camp down because Rwanda was descending into war.

The war continued for years, killing hundreds of thousands of people.

So instead of growing up to study gorillas, I study chimpanzees.

 You can’t always get what you want.

But if you try sometimes,

You might find,

You get what you need.

And what I needed was chimpanzees.

I needed chimpanzees because they are our closest living cousins.

Human family tree

 

 

 

 

 

 

Chimps and gorillas look a lot alike: hairy, knuckle-walking apes. The the two kinds of chimpanzees — “common chimpanzees” and bonobos — are more closely related to us than they are to gorillas.

And chimpanzees share a number of unusual traits in common with people.

They make and use tools – like this one here, who is using a stick to fish termites from their nest so she can eat them:

Golden fishing for termites.
Golden fishing for termites. (Photo by Michael Wilson)

 

 

 

 

 

 

Like humans, chimpanzees work in groups to hunter other animals.

And like humans, chimpanzees defend group territories, and sometimes gang up on members of other groups, attacking and killing their enemies.

It is this warlike behavior that I set out to study, looking for clues about how the origins and evolution of warfare in our own species.

So I went to study chimpanzees in Kibale Forest in western Uganda – much safer, I figured, than studying gorillas in war-torn Rwanda.

As it happened, though, the war in Rwanda spilled over into Congo, resulting in a huge war that eventually involved nine African nations and killed millions of people.

The first Congo war. http://en.wikipedia.org/wiki/First_Congo_War#/media/File:First_Congo_War_map_en.png
The first Congo war. http://en.wikipedia.org/wiki/First_Congo_War#/media/File:First_Congo_War_map_en.png

 

 

 

 

 

 

 

 

Kibale is just 30 miles from the border with Congo. On a clear day in Kibale you can see the snowcapped Ruwenzori Mountains that form that border.

And while the war raged in Congo, a Ugandan rebel group, the ADF, set up in those very mountains. Some of them were even rumored to be hiding in Kibale. The ADF bombed cafes and buses around Uganda, and attacked a school just 20 miles from us, burning 80 students alive.

At one point bandits attacked our village. They robbed and beat chimpanzee project field assistants, and shot and killed the brother of one of our employees.

And right around this time, one of the same field assistants who had been robbed found our chimpanzees beating on the freshly killed body of a male chimpanzee from another community.

The stranger’s body was covered in bites and other wounds, and his throat was torn out.

Why do chimpanzees do this?

Lots of other animals defend group territories, but in most species, they just chase their enemies away, rather than hunt them down and kill them. What’s going on?

Why do we kill?

One explanation for why we kill is the imbalance of power hypothesis, developed by Richard Wrangham and colleagues.

Behavioral ecologists think of aggression as the result of a cost-benefit calculation: animals use aggression as a strategy to get some benefit, when it looks like the benefit will be greater than the cost.

The benefits of aggression in chimpanzees are similar to those in other group territorial species: territory, food and mates.

But the costs of killing are low because of an unusual social structure that chimpanzees share with humans: fission fusion societies.

If we were gorillas, we would travel in a stable group all the time: a single male with his harem of females and kids.

But instead we live like chimpanzees: sometimes gathering in big groups, like we are now, and sometimes separating off into smaller groups.

For example, here are two neighboring territories: Blue and Red.

Slide11

 

 

 

 

 

Each territory has 10 males.

There’s not much food at the moment in the Blue territory, so the Blue males are traveling in small parties, mainly ones and twos.

But there’s more food in the Red territory. They can travel in bigger parties, including this one with six males.

 These six males have safety in numbers, so they go on a border patrol.

 Slide12

 

 

 

 

 There they find a single blue male off by himself.

 Slide13

 

 

 

 

Bad luck for the blue male! The red males surround him, gang up on him, and kill him.

Slide14

 

 

 

 

 

Now Blue only has 9 males.

Slide15 

 

 

 

 

With fewer males, Blue loses territory to Red. The Red males get the benefit of a larger territory with more food for themselves, their mates and their offspring.

The imbalance of power hypothesis makes some clear predictions.

For example:

Males should visit borders only when in larger groups.

Parties with more males should be more likely to approach strangers, to win fights, and to kill their enemies.

And winners should gain more territory.

I’ve spent much of the past 20 years testing these predictions.

I used playback experiments to test how males would respond to a stranger.

Slide17
Donor and John setting up the playback equipment. (Photo by Becky Sun)

 

 

 

 

 

 

 

In each experiment, I played back a single pant-hoot call from a foreign male.

A pant-hoot sounds like this:

 

(And this is what a professor imitating a pant-hooting chimpanzee looks like:)

Pant-hoot demonstration.
Pant-hoot demonstration.

 

 

 

Hearing a single stranger calling in the distance had a big effect on the chimpanzees.

Slide18
Rosa, Lope, Ipassa and Makoku looking towards an unexpected sound. (Photo by Becky Sun)

 

 

 

 

 

 

 

In parties with just one or two males, they looked towards the speaker, which was hidden some 300 m away. Sometimes they just stayed still, looking, but in about half the cases they slowly, cautiously walked towards the speaker.

In parties with three or more males, the response was totally different. They gave a loud “wraa!” response right after hearing the call, dropped down from their trees, and rapidly walked single file towards the speaker.

After each playback, we quickly packed up the speaker and carried it away, while one of us stayed at the speaker location to see what happened. Often that person was me.

I remember sitting there quietly in the undergrowth when suddenly I heard footsteps. I saw a line of males walking single file, their hair out, looking for someone to kill.

They glanced my way, but they weren’t interested in me. They knew who I was. They were looking for a stranger.

More recently, I’ve analyzed data from all the long-term study sites for chimpanzees.

Slide19

 

 

 

 

 

 

What I’ve found is that killing is widespread, and occurs at most study sites.

In cases of intergroup killing, the attackers had an average 8:1 advantage over the defenders.

Analysis of long-term data has found that groups with more males expand their territory and obtain more food for self, mates, and offspring.

Just like chimpanzees, people are sensitive to the costs and benefits of aggression, and they prefer low cost fights: unfair fights that they are likely to win.

In human warfare, numbers matter, but even more important is weapons. Whenever people have developed a military advantage they have used it to conquer.

The Mongols, for example, swept across Eurasia with their fast horses and mounted archers.

Slide20
http://www.manchuarchery.org/photographs-mongolian-archers

 

 

 

 

 

 

 

But conquest, in humans and chimpanzees, is a zero sum game. Any benefit for my group is a loss for yours.

This is a risky game to play. About 12% of chimpanzees die from violence – that’s about out of eight.

Slide21

 

 

 

 

 

 

The tables in this room seat about 8 people – so if were living in such a world, on average one person at each table would die from violence.

In human groups that live much like we did for most of our evolutionary history – as hunter gatherers and small scale tribal societies – the rate of death from violence is also about 12%.

For both chimpanzees and people, playing this zero sum game of group territorial behavior means a high risk of death by violence.

But unlike chimpanzees, people have found some ways out of the zero-sum trap and have learned to play positive-sum games.

This slide shows the risk of dying in battle from war in the 20th Century, for people worldwide:

Slide22

 

 

 

 

 

The two big spikes are the First and Second World Wars.

What’s really striking about this graph is that there haven’t been any more really big spikes since 1945.

Nuclear weapons have raised cost of war so much that there have been no great-power wars in 70 years

People have – so far—avoided the horrible costs of direct nuclear exchange.

People are also sensitive to the benefits of peace, and these have increased over time, as the world has gotten more interconnected through trade.

The Trans-Siberian Railway is one of many links in this international trade. It connects Russia with China, and now with Europe as well.

Slide23

 

 

 

 

 

I think back to my journey across Siberia. If I were a young male chimpanzee venturing so far from home, I would have been killed by the first group of foreign males I met.

But traveling deep into what had been enemy territory, I was never threatened. People can benefit from a stranger, if only by having someone to talk with, and share their vodka.

So what can chimpanzees tell us about war?

Slide24

 

 

 

 

 

 

War is natural, but it is not inevitable.

People, like chimpanzees, are sensitive to both costs and benefits.

We can reduce war by increasing its costs, and by increasing the benefits of peace.

And what gives me hope is that the people I’ve met traveling around the world – they don’t want mutually assured destruction. They want the simple things listed in the Pink Floyd song about in the Post-war Dream:

A place to stay.

Enough to eat.

Somewhere old heroes shuffle safely down the street.

You can relax on both sides of the tracks

And maniacs don’t blow holes in bandsmen by remote control.

And everyone has recourse to the law.

And no one kills the children anymore.

 

All that jazz

So last week the Nielsen ratings for 2014 revealed that jazz has become the least popular major musical genre for adults, falling behind classical music. Jazz accounted for 2% of all albums sold in 2014, or about 5.2 million albums. Which is only a bit more than the 4.5 million copies of the Frozen soundtrack album sold that year.

Music evolves. Jazz has existed for just over a century, and during that time it evolved rapidly, giving birth to forms like Dixieland, big band swing, bebop, cool, bossa nova, free jazz, fusion, and acid jazz. Jazz dominated popular music for a few decades, the 1920s-1940s, but since then has lived mainly on the fringes.

If we think of genres as groups of animals, then Classical composers would be like Mesozoic dinosaurs. They were huge in their day, and we can still admire their articulated skeletons in museums or orchestra halls, but the world they ruled is gone. They were eclipsed in the 20th Century by the mammals: hot blooded popular forms like blues, jazz, country, rock, soul, and hip hop.

I have long thought of jazz as being marginal but still alive and kicking. Maybe like marsupial music. Marsupials don’t rule the world, but hey, they’ve got Australia, and they had South America pretty much to themselves for a long time, and opossums have even managed to spread into much of North America.

Has jazz become a monotreme music?  https://aleonmiler.wordpress.com/2012/03/27/platypus-and-lady/
Has jazz become a monotreme music?
https://aleonmiler.wordpress.com/2012/03/27/platypus-and-lady/

But now I fear that jazz has become more of a monotreme. Back in the Jurassic, egg-laying mammals were the latest thing. But now there are just two major groups of monotremes: one species of platypus and around four species of echidna, confined to Australia and New Guinea. Monotremes are amazing, and well worthy of study and conservation, but they are pretty much an evolutionary oxbow lake, far from the mainstream. For the most part most people don’t even think about them.

Whichever depressing analogy is most fitting, marsupial or monotreme, jazz is well on its way to being a museum music: curated by music departments and Jazz at Lincoln Center, subsidized by festivals where the headliners are often anyone but mainstream jazz musicians, but nearly extinct in the wild.

This makes me sad, because I love jazz, and have spent many years listening to it and trying to play it.

I remember seeing the jazz band play at Taylorville Junior High when I was still in grade school. The long row of saxophones, shiny and gold, with strange bends and twists in the horns, and the music they made — I was hooked. I started playing saxophone soon after, and have tried to make progress on that horn ever since.

In 1982, the average age of the jazz audience was 29. By 2008, the average age had increased to 46. Jazz used to be music for younger people, but now its audience is about the same age as the audience for classical music, opera and ballet. A demographic status that doesn’t bode well for the future of any of these genres.

Music is always changing. Today’s music doesn’t sound like yesterday’s music. Part of that is due to cumulative culture: today’s music builds on yesterday’s music, and is written in response to it. Music also evolves rapidly as technology for making music changes. Beethoven couldn’t write for saxophone because it hadn’t been invented yet. Gershwin, Ravel and Prokofiev did write for saxophone, but by then mainstream Classical music was already ossifying, too conservative to fully admit this new instrument into its ranks. So the saxophone found its home in popular music instead, where  it reigned supreme for a few decades, especially the 1930s and 1940s, and lingered on as a popular solo break instrument into the 1980s. But saxophones have been superseded in popular music by more recent technologies: electric guitars in the 1950s and 1960s, then synthesizers in the 1970s, and later sampling and other electronic tools.

Another reason for the high rate of evolution in music may be its role in sexual selection. Back in 1871, Darwin not only invented the term “sexual selection,” but gave music as a likely example of it in humans.

it appears probable that the progenitors of man, either the males or females or both sexes, before acquiring the power of expressing their mutual love in articulate language, endeavored to charm each other with musical notes and rhythm. (Darwin 1871: 880)

Darwin thus argued that song in humans had much the same function as song in birds: attracting mates.

Unlike many songbirds, in humans both males and females sing and make other forms of music. Some people have argued that this is evidence against a sexually selected origin of music in humans. But song need not be produced by only one sex to be a courtship signal. In a number of bird species, both sexes sing, and duetting is important for maintaining pair bonds. See, for example, the duets of the wonderfully named happy wrens.

Nonetheless, in humans there seems to be a bias for males to be performing for female audiences. Analyzing a sample of 1,800 jazz albums, 1,500 rock albums and 3,800 classical music works, Geoffrey Miller (2000) found that

males produced about ten times as much music as females, and their musical output peaked in young adulthood, around age thirty, near the time of peak mating effort and peak mating activity. This is almost identical to the age and sex profiles discovered by Daly and Wilson (1988) for homicides, which they took as evidence for sexual selection shaping propensities for violent sexual competitiveness. (Miller 2000: 354)

The standard rock band basically looks like a lek, which Wikipedia defines as “an aggregation of males that gather to engage in competitive displays that may entice visiting females who are surveying prospective partners for copulation.”

In his book My Appetite for Destruction, Steven Adler, the founding drummer of the rock band Guns N’ Roses, tells a story about how in high school football practice he played especially aggressively to impress a particular cheerleader on the sidelines. He goes on to say that music is much the same thing for him:

I don’t know why I’m wired this way, but there are very few things in life that really light me up. And nothing focuses me or gets me going like chasing tail. Money, fame, status, power . . . nothing comes close to the pursuit of pussy. It gives me an intensity that brings out the fiercest side of my competitive spirit.

When I was with the band I had to score the best snapper after a concert. I loved parading around backstage and at the after parties with the pick of the litter. So whether it’s trying to score by making touchdowns or playing in a band, I love the ladies. Primo poon: accept no substitutes. (Adler 2011: 13-14)

In a lek, the pressure is strong to sound new, innovative, and distinctive. And like Milton Babbitt said, “Nothing gets old faster than a new sound.” So the pressure continues to come up with new and distinctive sounds.

In contrast, the average jazz jam session is sort of an anti-lek: a group of mainly male musicians playing old style music, not for a crowd of screaming teenage girls, but for almost no audience at all.

But even if music has its evolutionary roots in courtship signals, the beauty and power of music transcend those roots. You don’t need to be courting to appreciate the intricacies of a Bach fugue or the cunning way the melody navigates the chord changes of All the Things You Are. The strange power of music — the way we perceive particular combinations of sounds as beautiful or ugly or joyous or despairing — works regardless of whether we are in a mating mood or not.

Psychologist Mihály Csíkszentmihályi argued that “people are happiest when they are in a state of flow— a state of concentration or complete absorption with the activity at hand and the situation.” He frequently mentions playing jazz as an example of this. And maybe this is why I keep coming back to jazz. It makes me happy.

And in some ways, this is an amazing time to be a jazz fan. YouTube has hundreds of hours of music and video. Growing up, I knew jazz mainly from what we played in jazz band and what I could hear on late night public radio, tapes from friends, and the occasional album. I had only the vaguest idea of what any of these musicians looked like. I didn’t even know Miles Davis was black until Aunt Lynn gave me an album (Workin’ & Steamin’) with his picture on it. Now anyone with an interest and an internet connection can watch videos of jazz greats playing. There are websites offering detailed advice about how to play jazz. And I’ve been meeting younger players who really know their stuff.  So maybe there is hope this particular branch of music will stay alive, growing and evolving, even if the mainstream has long since moved on.

Adler, S. (2011). My Appetite for Destruction: Sex & Drugs & Guns N’ Roses. New York, HarperCollins Publishers.

Darwin, C. (1871). The Descent of Man and Selection in Relation to Sex. New York, The Modern Library.

Miller, G. (2000). Evolution of human music through sexual selection. The Origins of Music. N. L. Wallin, B. Merker and S. Brown, MIT Press: 329-360.

Evolution and Warfare Workshop at NIMBioS

I’m very excited to announce that NIMBIoS, the National Institute for Mathematical and Biological Synthesis, will be hosting a workshop, “Evolutionary approaches to the understanding of decentralized warfare,” September 16-18, 2015, at the University of Tennessee, Knoxville.

I am organizing this workshop along with Luke Glowacki (Harvard University), Anna Simons (Naval Postgraduate School) and Sergey Gavrilets (University of Tennessee).

Objectives: Warfare is a widespread and arguably universal practice of human societies. While war’s origins continue to be debated, warfare has occurred in most historically documented societies, from hunter-gatherers to nation-states. Its prehistoric traces can be found in fortifications, weapons, mass graves, and skeletal trauma. Given that it is a major source of mortality, warfare has potentially acted as a powerful source of selection for both biological and cultural evolution. In a reprise of the past – and in contrast to force-on-force, hierarchically organized wars among great powers – conflict today takes a number of decentralized forms, from urban gang fights to livestock raids, and from clan warfare to leaderless resistance and terrorism. Suggestive parallels exist between current patterns of warfare and those that typified subsistence-level societies. Consequently, examining psychological mechanisms that evolved under ancestral warfare conditions may shed important light on what motivates individuals during modern decentralized wars and why people resort to violence in intergroup conflicts. Given the availability of data from contemporary societies and the great damage caused by violent conflict, advancing our understanding of such conflict is both tractable and important. In this workshop, we will begin working toward an integrated approach to the study of warfare under decentralized or only loosely controlled conditions, combining empirical data, evolutionary theory, and mathematical models. We envision developing working hypotheses to answer several key questions about between-group conflict in general, and the nature of ‘decentralized warfare’ in particular. These hypotheses will be informed by evolutionary theory using data from diverse conflict settings. Our hypotheses will be articulated in a framework amenable to formal modeling that will point the way toward a multi-level predictive understanding of warfare.

Descriptive flyer (PDF)

Application deadline: May 17, 2015. To apply CLICK HERE.
Participation in the workshop is by application only. Individuals with a strong interest in the topic are encouraged to apply, and successful applicants will be notified within two weeks of the application deadline. If needed, financial support for travel, meals, and lodging is available for workshop attendees.

 

Kissing

So I got a call the other day to talk to a TV reporter about kissing. Valentine’s Day was coming up, and since it was also Darwin’s Birthday, it seemed fitting to talk about the evolution of this rather odd behavior. Moreover, even though my research focuses more on fighting and war than love and kisses, spending the last year living in France had me thinking about cultural variation in kissing.

People kiss a lot in France. Friends kiss each other when saying hello and when saying goodbye. Boys kiss girls, girls kiss girls, and boys kiss boys.  All this intimacy can make a shy person raised in the Upper Midwest feel quite awkward. And it presents all sorts of challenges. How well do you need to know someone before you kiss them? Do you actually touch the lips to the cheek, or just brush cheeks and kiss the air in their general direction? (Turns out its the latter.)

Though all this kissing might suggest an easy intimacy, in other ways the French are even more reserved than Americans. As French language and lifestyle expert Géraldine Lepère says, “Do not try to hug a French person. They will freeze.”

Adding to the challenge is that the number of kisses expected varies from region to region across France. In our area, Languedoc-Roussillon, three kisses were the norm.  But in other parts of France, the norm involves anywhere from one to five kisses. Greeting friends from those other regions was always a challenge. How many times do we kiss?

Geography of French kissing. http://all-that-is-interesting.com/map-of-french-kiss-customs
Geography of French kissing. http://all-that-is-interesting.com/map-of-french-kiss-customs

 

 

 

 

 

 

 

 

Thinking about all this cultural variation in greeting kisses made me wonder about the romantic kiss. Is it a human universal, or does romantic kissing show the sort of cultural variability that we see in greeting kisses? And what about kissing in our primate cousins?

Chimpanzees don’t have romantic kisses. But then they don’t really have romance. Mating is a quick business that last seven seconds or so, and the typical mating posture doesn’t bring the lips into close proximity. Females often scream and dart away after than mating rather than staying close to kiss and cuddle (though sometimes males do a bit of grooming of their partner in the afterglow).

Chimpanzees do kiss in other contexts, though, such as greeting and reassurance. Once at Lincoln Park Zoo in Chicago I saw two female chimpanzees engaged in a leisurely lip kiss that lasted at least ten minutes. But I don’t recall seeing anything like that in the wild.

Bonobos are reported to kiss more often, and to use their tongues when kissing. Frans de Waal writes, “French-kissing’ is totally absent in the chimpanzee, which engages in rather platonic kisses. This explains why a new zookeeper familiar with chimpanzees once accepted a kiss from a male bonobo. Was he taken aback when he suddenly felt the ape’s tongue in his mouth!” (de Waal, 1998: p. 103)

Unlike chimpanzees, bonobos frequently mate face to face, which would make romantic kissing more feasible. So perhaps romantic kissing in humans has something to do with our more bonobo-like mating postures.

In The Naked Ape, Desmond Morris suggested that kissing came from sharing food between mother and offspring. This is a classic example of ethological thinking, in which some puzzling, apparently useless behavior is interpreted as a ritualized version of an older, clearly functional behavior. But I’ve never liked this explanation. Partly I suppose because it’s a bit gross. But also, this isn’t something I’ve seen either people or other primates doing. I have seen human mothers pre-chew food for their children, but they transfer the food with their fingers, not their lips. And apart from Junior High stories about kissing couples sharing their chewing gum, food sharing doesn’t seem to play much role in romantic kissing in humans.

More recently, Evolutionary Psychologists have interpreted romantic kissing as a key component of mate selection in humans. By tasting a potential mate’s lips and saliva, kissers may be able to gain useful information about their health and perhaps even genetic quality and compatibility before taking any chances on actually combining their genetic material. One survey study of American college students found that women, more so than men, are reluctant to have sex with someone they haven’t kissed, and more likely to choose not to have sex with someone if they prove to be a bad kisser (Hughes et al., 2007). This makes sense given the sex differences in parental investment that are typical of mammals. Since women rather than men carry any resulting babies inside their bodies for months and then nurse them once they are born, women have a greater evolutionary interest in making sure they they screen potential mates for genetic quality.

Hughes et al. (2007) thus suggest that kissing is an evolved strategy, and argue that romantic kissing occurs in “over 90 percent of human cultures.” Kissing seems kind of a risky way to assess someone’s health, though. After all, if they turn out to be harboring some nasty infection, sharing their saliva is maybe not the best idea. Why not just a quick sniff of their breath instead?

Moreover, thinking about all the cultural variation in kissing in other contexts made me wonder whether romantic kissing was really so invariable.

Darwin, as usual, is way ahead of us here. In his 1872 book, The Expression of the Emotions in Man and Animals, he wrote that kissing was unknown in many non-European cultures:

We Europeans are so accustomed to kissing as a mark of affection, that it might be thought to be innate in mankind; but this is not the case. Steele was mistaken when he said “Nature was its author, and it began with the first courtship.” Jemmy Button, the Fuegian, told me that this practice was unknown in his land. It is equally unknown with the New Zealanders, Tahitians, Papuans, Australians, Somals of Africa, and the Esquimaux.

Darwin’s observation that romantic kissing is not a human universal is supported by a study that will be published in American Anthropologist later this year (Jankowiak et al., in press). This study examined 88 different cultures from the Human Relations Area Files, and also consulted with people working in various non-Western societies. They found that not only was romantic kissing not a human universal, it was only found in 40% of the cultures they examined. Strikingly, they found that romantic kissing was entirely absent in hunter-gatherers, the people whose societies are widely thought to most closely resemble the conditions in which our species has lived for most of our evolutionary history.

This finding seems to me an excellent example of the importance of good old fashioned Anthropology, in which the goal is to find document and explain human variation across the planet. If our picture of human behavior is based only on the behavior of our most convenient study subjects (e.g., American college students), we will come up with a badly distorted picture of our species.

In cultures with romantic kissing, pressing the lips clearly plays a big role in mate choice.  And the evolutionary logic for women being a bit more interested in the quality of kisses than men seems sound. But because kissing occurs only in a minority of human cultures, sex differences in preference for kissing must result from some more general mechanisms, rather than having evolved as part of a specific mental module for smooching.

Works cited:

Darwin, C. (1872). The expression of the emotions in man and animals. London, Murray.

Hughes, S. M., M. A. Harrison and G. G. Gallup (2007). “Sex differences in romantic kissing among college students: An evolutionary perspective.” Evolutionary Psychology 5(3): 612-631.

Jankowiak, W. R., S. L. Volsche and J. R. Garcia (in press). “Is the Romantic/Sexual Kiss a Near Human Universal?” American Anthropologist.

Morris, D. (1967). The Naked Ape: A Zoologist’s Study of the Human Animal .Jonathan Cape.

de Waal, F. B. M. (1998). Bonobo: The Forgotten Ape, University of California Press.

Irven DeVore

On Tuesday, 23 September, I lectured to my Primate Ecology and Social Behavior class about how methods of measuring behavior have changed since the first pioneering studies in field primatology. As an example of the importance of methodology, I used baboon troop progressions, a controversy starring Irv DeVore. That night, I learned from Greg Laden that Irv had died that same day, a couple of weeks shy of his 80th birthday.

I first met Irv twenty years ago, when I visited Harvard as a prospective graduate student. He sat at the big desk in the corner office of the Peabody Museum, at the top of the stairs. The bathroom outside his office stank of cigarette smoke because that’s one of the few places in the building he could get away with smoking. Irv looked a bit like Colonel Sanders: white hair, mustache and goatee, a tall southern gentleman, wearing a khaki field vest like he had just gotten back from safari and hadn’t had time to change clothes. The books packing the tall bookshelves included classics that Irv had edited: Primate Behavior: Field Studies of Monkeys and Apes (1965), Man the Hunter (1968) and others. From the walls hung artifacts from Africa: bows and arrows, spears, wood carvings.

We talked about baboons. At the time, I was working for Jeanne Altmann, managing data for the Amboseli Baboon Project, and had spent about ten months at Mpala Research Camp in Kenya habituating baboons for a Kenyan PhD student, Philip Muruthi. Irv told me about his own days studying baboons in Kenya.

Starting in 1959, as a student of Sherwood Washburn, Irv studied baboons in Amboseli and Nairobi National Park. At the time, very few people had studied primates in the wild in any detail. This was the same year that George Schaller began his pioneering studies of mountain gorillas, and a year before Jane Goodall began studying chimpanzees at Gombe. As this figure shows, Irv started studying baboons right at the start of an exponential increase in hours devoted to field studies of primates:

Time devoted to field studies of primates (from Altman, 1965)
Time devoted to field studies of primates (from Altman, 1965)

 

 

 

 

 

 

When I first met Irv, I was mostly ignorant of the many disputes in the history of baboon studies. The example I used in class the other day, about baboon troop progressions, was something that I only learned about later. It’s little more than a footnote now in primate studies, and perhaps not worth dwelling on, but is something I keep coming back to, as an example of methodology, an illustration of how science works, and a point of departure for thinking of Irv’s long and influential career.

By the 1950s, anthropologists were beginning to take seriously the idea that humans had evolved in Africa. Raymond Dart had discovered the oldest known hominin fossil, Australopithecus africanus, in South Africa (Dart, 1925). In attempting to reconstruct the likely behavior of Australopithecus, Dart drew on what was then known about baboons, which were the most conspicuous primates living where the fossil had been found:  on the open plains on the edge of the Kalahari Desert. Dart knew that baboons sometimes hunted and ate meat, which he used to support his view of Australopithecus as having made the transition from “fruit-eating, forest-loving apes” to  “the sanguinary pursuits and carnivorous habits of proto-men” (Dart, 1953).

Washburn hit on the idea of studying baboon behavior while at the 1955 Pan-African Conference in Prehistory in Northern Rhodesia, with Raymond Dart and Louis Leakey. Primarily a comparative anatomist, Washburn had dissected many baboons, which were considered vermin and could be shot at will. But at the Victoria Falls Hotel, Washburn began actually watching live baboons, and found their behavior fascinating, and relevant for testing many ideas about human evolution (DeVore, 1992).

Back in his home base at the University of Chicago, Washburn recruited DeVore to study baboons. At the time, Irv was a grad student in cultural anthropology, with no formal training in animal behavior. As a pioneering researcher, though, Irv quickly became the expert on baboon behavior. He and Washburn published their findings widely, in Scientific American, in edited volumes about primate behavior and human evolution, and in a series of educational films and pamphlets.

One of the puzzles in human evolution was how our ancestors could have survived on open plains inhabited by dangerous carnivores such as lions and leopards. DeVore and Washburn saw baboon troop progressions as an adaptation to keeping safe in this hazardous environment:

Illustration of a baboon troop progression from Hall & Devore (1965)
Illustration of a baboon troop progression from Hall & DeVore (1965)

A baboon troop that is in or under trees seems to have no particular organization, but when the troop moves out onto the open plains, a clear order of progression appears. Out in front of the troop move the boldest troop members-the less dominant adult males and the older juvenile males . . . Following them are other members of the troop’s periphery, pregnant and estrus adult females and juveniles. Next, in the center, comes the nucleus of dominant adult males, females with infants, and young juveniles. The rear of the troop is a mirror image of its front, with adults and older juveniles following the nucleus and more adult males at the end. This order of progression is invariably followed when the troop is moving rapidly from one feeding area to another during the day, and to its sleeping trees at dusk . . . (DeVore & Washburn, 1963)

There was a clear adaptive logic to this organization:

The arrangement of the troop members when they are moving insures maximum protection for the infants and juveniles in the center of the troop. An approaching predator would first encounter the adult males on the troop’s periphery, and then the adult males in the center, before it could reach defenseless troop members in the center. (DeVore & Washburn, 1963)

This idea that baboon societies were geometrically organized for protection appealed to people and became widely cited. As late as 1997 or 1998, I found a textbook in an elementary school in rural Uganda that contained a description of baboons that must have been adapted directly from DeVore’s publications. It faithfully replicated claims about the baboon troop progression, illustrated with line drawings of baboons.

Irv soon moved on from baboons to study hunter-gatherers and work in various ways to bring evolutionary theory into the study of human behavior. In the meantime, other researchers began studying baboons, including Stuart and Jeanne Altmann, who began doing fieldwork in Amboseli in 1963, soon after Irv’s pioneering studies there. Stuart was a leader in the newly emerging field of primatology, having studied rhesus macaques on Cayo Santiago and howling monkeys in Panama. As a graduate student of E. O. Wilson at Harvard, Stuart was one of the first researchers to use the term “sociobiology,” which he used to describe his approach to studying rhesus monkeys on Cayo. In his 1962 paper on rhesus monkeys, Stuart lists Irv as one on of the visitors to Cayo, sometime around 1957-58, so Irv must have visited Cayo before his own first trip to Kenya. Irv studied baboons for a few years; the Altmanns worked together for decades, establishing a long-term project that continues to examine many different aspects of baboon behavior and ecology.

In the midst of documenting many aspects of baboon lives, Stuart made a concerted effort to study baboon progressions (Altmann, 1979). This passage from the methods section of his 1979 paper illustrates the meticulous observations he undertook to test the hypothesis that baboon movements represent an orderly geometry:

Baboons in progressions were censused at opportune times during the course of several projects. With experience, we learned to anticipate their route of progression. From a position ahead of and to the side of the anticipated route, we selected a line of sight that was as free as possible of obstructing vegetation. We picked out some small visual marker, such as a rock or the edge of a distant tree, that would clearly fix the line of sight or ‘counting point’. Then, as each individual in turn walked past this imaginary line, its age-sex class was recorded. Whenever two individuals were close together as they passed the counting point, the order was determined ‘horse race style’, i.e. depending on whose nares crossed first. If an individual turned back across the counting point, then crossed it a second time, it was counted as being in its second position. Whenever possible, individual identifications were made. . . .  During many of these censuses, a second observer not only confirmed observations but also continued to observe individuals that were inadequately observed by the primary observer, who remained with eyes fixed on the counting point so as not to miss the next individual. Observations were facilitated by using 7x, 35mm (or 10x, 50 mm) binoculars, propped in position so that the observer could keep continuous watch on the counting point. Data were usually dictated into a portable cassette recorder, thereby eliminating any need to look down to write. (Altmann 1979: 49-50)

Analyzing data recording during many such observations, Stuart found that baboon progressions were essentially random, rather than strictly ordered:

In none of the baboon groups that we have studied is there a fixed progression order, either by individual or by age-sex class. Indeed, we have seen members of virtually every age-sex at every place in the group, including adult females with small, clinging infants in the front and rear of the group. (Altmann, 1979: 51)

So, as it turns out, Irv’s initial hypothesis about the geometry of baboon troop progressions was wrong. Irv would later tell his class of 500 students that he had done it all wrong, that none of the methods he used then would pass muster today. But Irv was one of the first. He was proud of his baboon films, which he said were the  first wildlife films to use synchronized sound (rather than simply adding sound in later). These films served as many students’ first introduction to baboon behavior. He drew attention to baboons and other wild primates as important subjects for understanding human nature and evolution. He inspired and taught generations of students who followed, including many who would become major figures in primate studies, including John Fleagle, Peter Rodman, Sarah Hrdy,  Patricia Whitten, Jim Moore, Barbara Smuts, Karen Strier, and others.

Irv was my co-advisor for my first years in grad school, and though this formal role lasted only a year or two, I learned a great deal from him , especially while serving on the team of Teaching Fellows for his giant lecture course, Science B-29.

While Irv nurtured and inspired primatologists for his entire career, long before I met him he had switched his focus back to humans. Starting in the mid-1960s, he helped launch modern studies of hunter-gatherers, advising Richard Lee and a series of others in studies of the !Kung San, who as a result became the proto-typical hunter-gatherers. The !Kung exhibit on the ground floor of the Peabody Museum beautifully depicted the material culture and lifeways documented by this project, with video interviews describing the rapidly changing conditions of their lives in more recent years.

In the 1970s, Irv embraced and promoted sociobiology, mentoring pioneers in the field including Bob Trivers and Sarah Hrdy. In the 1980s he assisted at the birth  of evolutionary psychology, advising John Tooby and mentoring others who became leaders of this new field.

When I was a graduate student, writing up my thesis, Irv dropped by my office one day, and noticed a copy of Primate Behavior on my shelf. He asked, “What are you doing with that old thing?”

Perhaps it was false modesty, but he seemed genuinely surprised that anyone would consult his old tome. I think he felt keenly that his earliest work had been supplanted by the rapid progress of primatology.

His obituary in the New York Times states:

While true that he never wrote a groundbreaking book that lasted the ravages of time, he was most proud of his students and spent his life nurturing them, mentoring them (as long as that didn’t include actually writing the letter of recommendation) and forcing his wife to edit their theses.

Irv published a number of books and other works, but his  list of publications doesn’t come close to reflecting his intellectual influence.

For evolutionary anthropology, Irv DeVore played a role a little bit like that played by Socrates in Greek philosophy.

As far as we know, Socrates never wrote anything. Instead, Socrates served as a teacher, asking questions, probing minds, encouraging people to question received wisdom.

Socrates never held a university position, or taught students in a formal classroom. Irv was a professor at Harvard and regularly taught a class of 500. However, like Socrates, Irv was most influential in informal settings. In Plato’s dialogues, the main source of information we have about Socrates, we often see Socrates as a guest at dinner parties. Irv seems to have been most at home, and most influential, in the Simian Seminars, the informal meetings that took place a couple of times a month at his home.

By the time I started grad school, the Simian Seminars were mainly the stuff of legend. We saw Irv regularly, as a lecturer, in seminars, and at beer hour (where he complained about the bitter, hoppy microbrews that the grad students favored), but the heyday of the Simian Seminars seems to have been from the 1970s through the early 1990s. Sarah Hrdy writes about them here.

In Plato’s Republic, Socrates discusses philosophy with a gathering of young men. It’s basically a dinner party. The discussion begins with an exchange between Socrates and an old man, Cephalus, who, seeing the end of his life approaching, busies himself with making sacrifices to the gods, to make sure things go well for him in the afterlife. Cephalus is pious and conventional. The conversation really gets going only after Cephalus leaves to make more sacrifices to the gods.

The Simian Seminars seem to have been a place where old Cephalus was not invited: a safe zone from pieties and conventional thinking.

At Simian Seminars almost no idea or topic was too sensitive, too politically incorrect or too bawdy to be off limits. This openness was made possible by an atmosphere of mutual trust, respect, and affection, which was very deliberately cultivated by the DeVores. (Hrdy, 2005)

In The Republic, the main impiety committed by Socrates was to talk about Justice without reference to the gods. As Plato describes in another work, The Apology, in the end Socrates was tried and executed for impiety. Among his crimes: teaching the young that the planets were not gods but were instead made of stone. But while Socrates may have held materialist views in regards to the planets, he still talked frequently of gods, daemons, souls, and an ideal world, arguing that the material world we see around us is a mere shadow of a higher reality.

Irv promoted an even more profound impiety: a serious embrace of evolutionary thinking. Daniel Dennett describes evolution as “the universal acid” (Dennett, 1996). It cuts through everything. Irv saw this and embraced it, and encouraged his students and friends and colleagues to think hard about what an evolutionary understanding of human nature really means.

Unlike Socrates, Irv was never tried for thought crimes, or forced to drink hemlock. But he did attract critics and and controversy. In Primate Visions , Donna Haraway uses DeVore as her main example of “the bad old days” before primatologists took notice of female primates. The schools of thought that Irv championed, sociobiology and evolutionary psychology, have long attracted controversy, and have been criticized by some for having a sexist bias. At least some of this criticism seems to result from people focusing on the titles rather than the contents of books. For example, many people seem to think that Lee and DeVore’s 1968 book Man the Hunter is devoted to celebrating the macho side of human evolution. Those who have read the book, though, will know that the authors actually argued against some widely held male-centered views. For example, Lee and DeVore argued that hunter-gatherer societies are often not organized along lines of male kinship (in contrast to the prevailing view at the time). Although the book’s title emphasized the meat hunted by men, inside the book the authors emphasized the importance of plant foods, which were mainly collected by women.

Because Socrates wrote nothing that survives, we know about him only from what was written by others. His followers, Plato and Xenophon, depict Socrates as a paragon of virtue and intellect; the playwright Aristophanes depicts Socrates as a clown. Similarly, Irv is perhaps better known from the words of his disciples and detractors than from his own work. And while detractors depicted Irv as someone focused on alpha male baboons and hunting men, as a mentor Irv championed both his male and female students. In Plato’s dialogues, only men participated in the philosophical discussions with Socrates. In the 1970s, some 2300 years later, women were still often excluded from important discussions. As Sarah Hrdy describes, though, the Simian Seminars welcomed women from the very beginning:

For many graduate students, these gatherings were the core of an unbelievably heady education. The format was especially important for women students, who in those days would often have been excluded from post-seminar gatherings where men talked out the issues over a beer, somewhere else. (Hrdy, 2005)

Irv was a pioneer. He was not a master of collecting or analyzing large datasets. But he was a great story teller. As a lecturer, he held the attention of hundreds of undergraduates every semester for decades.  Students laughed at his jokes and remembered details of his stories for years to come. He inspired many people to go out and check his stories, to prove him right or wrong. Most importantly, his overall vision of how to answer questions about human nature is, I think, spot on. To understand human nature, we need to take evolutionary theory seriously. We need to approach the world with an open, critical and creative mind. We need to test hypotheses with empirical data, not just philosophical introspection. We need to pay particular attention to the behavior and ecology of our primate cousins, and to people living as hunter-gatherers. Evolutionary principles hold enormous promise for explaining the behavior of people everywhere and everywhen. And in a lifetime devoted to implementing this vision, Irv championed collaborative work, took chances on unconventional students and ideas, and was not afraid to admit when he was wrong.

Irv DeVore at his last lecture, 15 December 2000. (Photo by Randall Collura)
Irv DeVore at his last lecture for Science B-29, 15 December 2000. (Photo by Randall Collura)

 

 

 

 

 

 

 

 

References

Altmann, S. A. (1962). “A field study of the sociobiology of rhesus monkeys, Macaca mulatta.” Ann N Y Acad Sci 102: 338-435.

Altmann, S. A., Ed. (1967). Social Communication among Primates. Midway reprints. Chicago, University of Chicago Press.

Altmann, S. A. (1979). “Baboon progressions: order or chaos? A study of of one-dimensional group geometry.” Animal Behaviour 27: 46-80.

Dart, R. A. (1953). “The predatory transition from ape to man.” International Anthropological and Linguistic Review 1(4): 201-218.

Dennett, D. C. (1996). Darwin’s Dangerous Idea: Evolution and the Meanings of Life. New York, Simon & Schuster.

DeVore, I. and S. L. Washburn (1963). “Baboon ecology and human evolution.” African Ecology and Human Evolution. C. F. Howell and F. Bourlière, Eds.. Chicago, Adline: 335-367.

DeVore, I. and S. L. Washburn (1992). “An interview with Sherwood Washburn.” Current Anthropology 33(4): 411-423.

Hall, K. R. L., & I. DeVore (1965). “Baboon social behavior.” Primate Behavior: Field Studies of Monkeys and Apes. I. DeVore, Ed. New York, London: 53-110.

Haraway, D. J. (1989). Primate Visions: Gender, Race, and Nature in the World of Modern Science. New York, Routledge.

Hrdy, S. B. (2005). “Milestones for Irv DeVore and the Simian Seminar.” Evolutionary Anthropology 14: 90-92.

Lee, R. and I. DeVore, Eds. (1968). Man the Hunter, Aldine Transaction.

Plato (1991). The Republic of Plato, Basic Books. Translated by Allan Bloom.

 

Human Impacts

Our recent paper on lethal aggression (Wilson et al., 2014) has attracted lots of attention, most of it positive. Not surprisingly, though, some critical responses have also emerged. Copied below is our response to one of these critiques.

John Horgan at Scientific American devoted a blog post to critiquing the paper — though this critique is not really focused on the paper, but on whether the paper’s findings support what Horgan calls the “deep roots theory of war.” Horgan later published a critique by Brian Ferguson, the main advocate of the Human Impacts Hypothesis. In introducing this critique, Horgan offered to post responses from any of the original paper’s authors. We therefore have written a response, which is now posted here. In case it might be useful, I’ve copied it here as well:

Human impacts are neither necessary nor sufficient to explain chimpanzee violence (or bonobo non-violence)

Michael L. Wilson, Christopher Boesch, Takeshi Furuichi, Ian C. Gilby, Chie Hashimoto, Catherine Hobaiter, Gottfried Hohmann, Kathelijne Koops, Tetsuro Matsuzawa, John C. Mitani, David Morgan, Martin N. Muller, Roger Mundry, Anne E. Pusey, Julia Riedel, Crickette Sanz, Anne M. Schel, Michel Waller, David P. Watts, Frances White, Roman M. Wittig, and Richard W. Wrangham[1]

In response to our recent paper (Wilson et al., 2014), Brian Ferguson (2014) critiques the methods we used to test whether chimpanzee violence is the result of human impacts. As Joan Silk notes in her commentary on our paper, “These results should finally put an end to the idea that lethal aggression in chimpanzees is a non-adaptive by-product of anthropogenic influences — but they will probably not be enough to convince everyone” (Silk, 2014: 321).

We expect that for the majority of primatologists, and among the wider community of animal behavior researchers, the results of our study are neither surprising nor controversial. But for those hostile to the idea that human violence relates in any way to biology or adaptive behavior, the Human Impacts Hypothesis (HIH) offers an out. Violence among our ape cousins is, in this view, the result of human contact, not the result of evolution favoring aggression as a strategy. The argument closely parallels Ferguson’s earlier argument that violence in tribal societies is mainly the result of contact with outsiders, especially European imperialists (Ferguson, 1990).

In contrast to some critics, Ferguson recognizes that “there is no question that chimpanzees have the capability to make war and have done so on occasion” (Ferguson, 2011: 249). Ferguson’s critiques thus represent a departure from what we might call the “strong anti-adaptationism” of previous proponents of the HIH. For example, Power (1991) argues that chimpanzee violence is a non-adaptive response to frustration caused by restrictive feeding methods at the first long-term study sites of chimpanzees, Gombe and Mahale. Ferguson embraces Power’s hypothesis that feeding chimpanzees made them more violent, but in contrast to Power, he argues that chimpanzee violence is mainly the result of resource competition, which is exacerbated by human activities such as feeding and deforestation. This argument differs little from arguments that behavioral ecologists regularly make to explain chimpanzee violence. For example, intercommunity violence in chimpanzees is strongly associated with competition over food resources. At Kanyawara, intercommunity encounters occurred most frequently when key food species were abundant in areas bordering neighboring communities (Wilson et al., 2012). Lethal aggression is strongly associated with territorial expansion at Ngogo (Mitani et al., 2010) and Gombe (Goodall, 1986), and by expanding territory chimpanzees increase the amount of food available to themselves, their mates and offspring (Williams et al., 2004; Pusey et al., 2005).

However, in his critique, Ferguson seems to conflate “resource competition” with “disturbance brought about by the actions of people.” Resource competition is not necessarily a “disturbance”, nor does it occur only as a consequence of “disturbance.” Instead, resource competition is a routine part of existence for living things. This is one of the central premises of evolution by natural selection, and evolutionary disciplines such as behavioral ecology. Ferguson therefore appears to agree with us that violence is an adaptive strategy for resource competition. And we agree that actions of people can sometimes affect resource competition in other animals, for example by adding a valuable, concentrated resource (Wrangham, 1974), or by removing key resources such as fruit trees, increasing competition for available land (Goodall, 1977). What we disagree on is whether the evidence indicates that human impacts are the main cause of chimpanzee violence.

Ferguson argues that “human impact must be approached in historical detail.” The 30 co-authors of our paper are deeply familiar with the historical details, with many of them having been involved in these long-term sites for decades. But historical awareness does not preclude a scientific approach. Clear predictions emerge from the hypothesis that human impacts cause chimpanzees to kill. We have sought to test those predictions systematically. We also appreciate that our study sites and study populations, and the human populations that now surround those sites, have complex histories that long pre-date our research projects, and that we should be aware of this fact despite the difficulties of reconstructing these histories. However, we are also concerned with history in another sense: the evolutionary history of chimpanzees. For the great majority of this history, chimpanzees and their immediate ancestors could not have been subject to “disturbance” of the kinds that Ferguson and other proponents of the HIH invoke.

When introducing Ferguson’s critique, John Horgan writes of confirmation bias, which is indeed a concern in any scientific endeavor. To counter this bias, scientists use tools such as collecting quantitative data and using statistical methods to test which models best explain the observed data. In our study, we sought to use methods that are objective and transparent, and which would provide well-substantiated answers, whether they agreed with our prior opinions or not.

In contrast, the “holistic” approach promoted by Ferguson is vulnerable to confirmation bias. Without clearly defining variables such as disturbance, and without using quantitative data and statistical methods designed to test whether a given set of results is likely given the available sample size, efforts to compare contrasting interpretations of a given set of data risk degenerating into cherry picking and special pleading.

Ferguson argues that “[t]he three measures Wilson et al. created to test for human impact are questionable.” However, he agrees in principle with each of these measures, and offers no quantifiable alternatives.

He states that our first measure, “artificial provisioning of food, is good, where it applies, though the impact of provisioning varies by how it is carried out and other conditions of food availability.” By this Ferguson presumably refers to the argument of Power (1991) that the “restricted” provisioning at Gombe and Mahale is what frustrated chimpanzees and (in Power’s view) fundamentally changed their behavior.

We do not dispute that providing food can change the behavior of chimpanzees and other animals. Wrangham (1974) found that at Gombe, chimpanzees and baboons were more aggressive in the feeding area than when foraging for natural foods away from the feeding area. What is clear from our study, however, is that provisioning is neither necessary nor sufficient for chimpanzees to kill.

We examined data on both chimpanzees (18 communities at 10 study sites) and bonobos (4 communities at 3 study sites). Of these sites, provisioning occurred at two chimpanzee sites (Gombe and Mahale) and one bonobo site (Wamba).

Evidence for lethal aggression has been found in seven of the of eight never-provisioned study sites (Budongo, Fongoli, Goualougo, Kalinzu, Kibale, Kyambura, Taï); the only exception is the small, isolated population at Bossou. Ferguson notes that “sites marked P for provisioning cluster (4 out of 7 cases) toward the high end of the killing distribution.” Fair enough, but the two highest rates of killing are for sites where chimpanzees were never provisioned. Moreover, at Mahale and Gombe, killings have continued to be observed long after provisioning ended (in 1987 and 2000, respectively). Killings by never-provisioned chimpanzees have also been reported at shorter-term study sites not included in our study, including Loango in Gabon (Boesch et al., 2007), as well as Conkouati-Douli National Park, Congo, where male wild-born, captive chimpanzees released into the wild were attacked by resident chimpanzees (Goossens et al., 2005).

Ferguson claims that “Provisioning’s statistical association with killing, however, is diluted by two other sites,” Mahale’s K-group and Wamba. “Diluted” is an odd choice of words here; if provisioning causes chimpanzees to become violent, then presumably every community provides relevant data, rather than dilution. Excluding K-group from the analysis would involve picking and choosing, excluding any data that doesn’t fit the expectation (in other words, guaranteeing confirmation bias).

Provisioning is thus clearly not necessary for chimpanzees to kill. Nor is it sufficient for killing to occur. Killings have been observed at both of the historically provisioned chimpanzee sites, but the observed and inferred killings by the Mitumba community at Gombe occurred only after provisioning ended there (Wilson et al., 2004). (We note, though, that one infanticide is suspected to have occurred at Mitumba during the time that Mitumba chimpanzees were provisioned (Pusey et al., 2008)).

Killings have not been observed at the provisioned bonobo site (Wamba). The one suspected bonobo killing took place at a non-provisioned site (Lomako). Ferguson notes that bonobos are a different species. Of course, this is true. But if provisioning causes chimpanzees to kill, why should it not cause other species to kill, especially closely related species?

Ferguson argues that Wamba should not be included in the analysis because bonobos are a different species. Fair enough; and indeed, in Table 3, we present results focused on just chimpanzees, excluding bonobos, and found that provisioning history did not explain variation in rates of killing among chimpanzee communities. But we also note that Ferguson has previously written that violence in chimpanzees is the result of social learning, proposing that bonobos would behave like chimpanzees if they experienced similar conditions (“What would happen if a bonobo were raised among chimpanzees or vice versa? I expect their behaviors would reflect the local custom” (Ferguson 2011: 255)). Following this line of logic seems to suggest to us that exposing bonobos to the same stimulus as chimpanzees (provisioned food) should result in a similar increase in aggressive behavior. But the one suspected case of killing by bonobos occurred at the never-provisioned site of Lomako, rather than the provisioned site of Wamba.

In our view, the much less frequent occurrence of violent aggression in bonobos compared to chimpanzees raises interesting questions about the evolution of non-violence as well as violence.

We note with interest, though, that Ferguson’s argument for provisioning is profoundly different from Power’s argument. Power argued that restricted provisioning fundamentally changed the behavior of chimpanzees at Gombe and Mahale, and that a wide range of chimpanzee behaviors reported by researchers there were the result of provisioning: male dominance hierarchies, despotic alpha males, possessive sexual behavior, closed membership of social groups, territorial behavior, female dispersal, hunting of monkeys, and intergroup killings. Studies of never-provisioned chimpanzees have found that all of these behaviors occur in the absence of provisioning. We can therefore reject the idea that chimpanzee behavior is fundamentally altered by provisioning. And indeed, instead of following Power’s argument that chimpanzee violence is maladaptive, Ferguson accepts that chimpanzee violence is an adaptive component of resource competition.

As a second measure of human impacts, we examined size of protected area. Ferguson notes that “some chimpanzee groups living within large protected areas have been heavily impacted.” Fair enough. That is why we conducted multivariate analyses considering several different variables. However, size of protected area is a measure that is readily quantified, and is likely important both for chimpanzee conservation and as a general measure of the degree to which chimpanzees have been affected by human activities. Like our other measures of human disturbance, however, size of the protected area did not have a consistent effect on rates of violence.

Our third measure of human impacts was an index of disturbance, based on a method developed by Naomi Bishop and colleagues for assessing the impacts of human activities on Hanuman langur monkeys in India (Bishop et al., 1981). Ferguson agrees that these measures “work well as a general index of over-all human impact,” but complains that “they do not work as predictors of intensified violence.” Similar complaints could be made of any effort to quantify human disturbance, because what exactly qualifies as disturbance is never clearly stated. However, it is worth pointing out that the disturbance index developed we used was originally developed to address a controversy over causes of infanticide (Bishop et al., 1981).

Importantly, for our disturbance rankings, each site director ranked their own site without prior knowledge of the rankings of other researchers. These rankings thus provide an independent estimate of disturbance made by the people who best know each of these sites.

Ferguson notes that Budongo has been exposed to various forms of lumber extraction, and other chimpanzee sites have experienced “islandization.” Fair enough. As primatologists actively involved in conservation efforts, we are deeply familiar with such issues at our sites. Capturing all of these different effects in a single variable, or a single index that combines several measures of disturbance (the approach we used), can never be wholly satisfactory. But we believe that the rankings that we did for our study do correlate reasonably well with the degree to which these different sites have been affected by humans. Goualougo is clearly the least affected chimpanzee site, and Bossou the most. Kanyawara, at the edge of Kibale National Park, has a higher disturbance rating than Ngogo, at the center of the park. We do not argue that our index is perfect, but we are not aware of a better one.

Ferguson points to many different possible impacts: provisioning, habitat clearance, timber extraction, hunting, and so on. Some of these could well have an effect on chimpanzee violence, by (for example) increasing the intensity of competition for resources. This is an adaptationist argument following standard theory in behavioral ecology, and as such, is an approach that we find reasonable. It is the fact that these are reasonable questions that motivated us to conduct our study. Given the possibility that human activities can affect rates of violence in chimpanzees, it is important to investigate the extent to which the observed patterns of violence reflect human impacts. This is what we have attempted to do, using data that are quantifiable, systematic, defined using the same criteria across study sites, and using a statistical approach that allows us to test predictions from multiple contrasting models. We found that human impacts did not explain the variation in rates of lethal aggression as well as other factors. Eastern chimpanzees killed more often than western chimpanzees, which killed more often than bonobos. Communities with more males and communities living in denser populations killed more frequently than communities with fewer males and sparser populations.

It is not at all clear why chimpanzees should react this way when exposed to humans, but not bonobos, baboons, or other species. For example, baboons have been studied at Gombe almost as long as chimpanzees and have been influenced by human activity. But they have not been observed to participate in coalitionary killing. What accounts for such differences between species when exposed to precisely the same human impacts? The absence of coalitionary killing in baboons makes sense from an evolutionary perspective (Wrangham, 1999), but is inexplicable from an anti-adaptationist perspective.

Moreover, chimpanzees and humans are far from the only species to engage in lethal aggression. Fatal fighting occurs widely among animals, and includes a broad range of examples, such as fatal fights among male spiders competing for mating opportunities (Leimar et al., 1991) and the killing and consumption of male spiders by female spiders, after (or sometimes during or even before) the males have mated (e.g., Andrade, 1996). Most such fatal fighting involves fights between individuals over a highly valuable resource. In contrast, coalitionary killing occurs in fewer species, and seems mainly limited to certain social insects, social carnivores such as wolves, lions and spotted hyenas, and a few primates, including humans and chimpanzees (Wrangham, 1999). Why coalitionary killing occurs in these species but not others is explicable, in principle, using the comparative method to develop testable hypotheses. An anti-adaptationist approach promises no such explanatory power.

Whether chimpanzee violence is adaptive or not, is a question for which we do not yet have a definitive answer. Answering this question in full requires information on reproduction and information on individual participation in violence, which is available for only a few sites and which has not yet been analyzed. Additionally, chimpanzees (like humans and other animals) may sometimes make mistakes, participating in killings that result in fitness (i.e. reproductive) costs. Whether a given behavioral strategy is adaptive depends on average effects of traits. Given these caveats, previous studies provide evidence in support of the view that chimpanzee violence provides fitness benefits to the attackers. Mitani et al. (2010) found that the intergroup killings by the Ngogo community were associated with substantial territorial expansion in the area where disproportionately many of the killings had taken place. Studies at Gombe provide evidence that larger territories provide important fitness benefits, including more food, as indicated by heavier individual body weights, controlling for age and reproductive condition (Pusey et al., 2005) and shorter inter-birth intervals for females (Williams et al., 2004). Males who enlarge their territory thus provide more food for their mates and offspring, enabling faster reproduction, and thus greater reproductive success for the aggressors.

In his critique, Ferguson mostly ignores the second focus of our paper: the pattern of attackers and victims. We found that most participants (92%) were male, as were most victims (73%). Most victims were members of other communities (63%). Intercommunity killings generally involved gang attacks, in which attackers outnumbered victims by a factor of 8:1. These patterns make sense when seen as adaptive strategies. Male chimpanzees defend group territories; eliminating members of rival communities enables males to increase the amount of food available to themselves, their mates, and offspring (Williams et al, 2004; Pusey et al., 2005; Mitani et al., 2010). Chimpanzees prefer to attack when the odds are in their favor (Wrangham 1999; Wilson et al., 2012). Viewing these behaviors solely as a non-adaptive response to human disturbance provides no insights into why attacks mainly involve males attacking members of other groups when the odds are in their favor.

The question of what, if anything, chimpanzee violence has to do with human warfare is one we did not address in our paper. We expect that among our 30 co-authors some diversity of opinion exists on this topic. We would all agree, though, that definitive claims about human behavior need to be based on data from humans.

Nonetheless, there are some important things we can learn from chimpanzee studies. Our study examines lethal aggression broadly, including infanticide and within-community violence. Despite this, the criticisms of Ferguson (as well as John Horgan’s earlier post) focus mainly on intercommunity killing, and its relevance to studies of human warfare. Ferguson, Horgan, and many others argue that warfare has a relatively recent origin (within the past 10,000 years (Ferguson, 2003)), due to some relatively new phenomenon, such as agriculture, or settled societies, or food storage, or property rights, or ideology, or new kinds of weapons. Chimpanzees have none of these things. They do sometimes use weapons (sticks and stones) but they don’t generally use them to kill each other. So the documentation of warlike behavior in chimpanzees shows that similar behavior could have occurred in humans long before the origin of agriculture and other evolutionarily recent innovations. It also raises the intriguing possibility that humans and chimpanzees share similar patterns of violence due to our shared evolutionary history; we may have inherited these patterns of behavior from our common ancestor.

As many have noted, however, and as we fully recognize, the existence of bonobos, with their much less violent societies, highlights the need to be cautious in how much we infer along these lines. It is possible that the lineages leading to humans and chimpanzees have both become more violent, or that the lineage leading to bonobos has become more peaceful over evolutionary time. We don’t yet know the answer to this question.

We heartily agree with Silk’s point that “Humans are not destined to be warlike because chimpanzees sometimes kill their neighbours” (Silk, 2014: 322). Variation in rates of warfare among countries today, and across historical time, clearly show that people can develop institutions and mechanisms that reduce the frequency and severity of warfare (Gat, 2006; Pinker, 2011). Chimpanzee communities also vary considerably in their rates of intercommunity violence. As we have found, this variation is better explained by differences among species, populations, and demography than by human impacts (Wilson et al., 2014).

References

Andrade, M. C. B. (1996). “Sexual selection for male sacrifice in the Australian redback spider.” Science 271(5245): 70-72.

Bishop, N., S. B. Hrdy, J. Teas and J. Moore (1981). “Measures of human influence in habitats of South Asian monkeys.” International Journal of Primatology 2(2): 153-167.

Boesch, C., J. Head, N. Tagg, M. Arandjelovic, L. Vigilant and M. M. Robbins (2007). “Fatal chimpanzee attack in Loango National Park, Gabon.” International Journal of Primatology 28: 1025-1034.

Ferguson, R. B. (1990). “Blood of the Leviathan: Western contact and warfare in Amazonia.” American Ethnologist 17(2): 237-257.

Ferguson, R. B. (2003). “The birth of war.” Natural History 112(6): 28-35.

Ferguson, R. B. (2011). Born to Live: Challenging Killer Myths. Origins of Altruism and Cooperation. R. W. Sussman and C. R. Cloninger: 249-270.

Ferguson, R. B. (2014). “Anthropologist Brian Ferguson challenges claim that chimp violence is adaptive.” Retrieved 19 September 2014, from http://blogs.scientificamerican.com/cross-check/2014/09/18/anthropologist-brian-ferguson-challenges-claim-that-chimp-violence-is-adaptive/.

Gat, A. (2006). War in Human Civilization. Oxford, Oxford University Press.

Goodall, J. (1977). “Infant killing and cannibalism in free-living chimpanzees.” Folia Primatol 22: 259-282.

Goodall, J. (1986). The Chimpanzees of Gombe: Patterns of Behavior. Cambridge, Massachusetts, Belknap Press.

Goossens, B., J. M. Setchell, E. Tchidongo, E. Dilambaka, C. Vidal, M. Ancrenaz and A. Jamart (2005). “Survival, interactions with wild conspecifics and reproduction in wild-born orphan chimpanzees following release into Conkouati-Douli National Park, Republic of Congo.” Biological Conservation 123: 461-475.

Leimar, O., S. Austad and M. Enquist (1991). “A test of the sequential assessment game: fighting in the bowl and doily spider Frontinella pyramitela.” Evolution 45(4): 862-874.

Mitani, J. C., D. P. Watts and S. J. Amsler (2010). “Lethal intergroup aggression leads to territorial expansion in wild chimpanzees.” Current Biology 20(12): R507-R508.

Pinker, S. (2011). The Better Angels of Our Nature: Why Violence Has Declined, Viking.

Power, M. (1991). The Egalitarians—Human and Chimpanzee: An Anthropological View of Social Organization. Cambridge, Cambridge University Press.

Pusey, A. E., G. W. Oehlert, J. M. Williams and J. Goodall (2005). “The influence of ecological and social factors on body mass of wild chimpanzees.” International Journal of Primatology 26: 3-31.

Pusey, A. E., C. Murray, W. R. Wallauer, M. L. Wilson, E. Wroblewski and J. Goodall (2008). “Severe aggression among female chimpanzees at Gombe National Park, Tanzania.” International Journal of Primatology 29(4): 949-973. get pdf

Silk, J. B. (2014). “Animal behaviour: The evolutionary roots of lethal conflict.” Nature 513(7518): 321-322.

Williams, J. M., G. Oehlert, J. Carlis and A. E. Pusey (2004). “Why do male chimpanzees defend a group range? Reassessing male territoriality.” Animal Behaviour 68(3): 523-532.

Wilson, M. L. (2012). Long-term studies of the Gombe chimpanzees. Long-term Field Studies of Primates. P. Kappeler and D. P. Watts. Heidelberg, Springer-Verlag: 357-384. get pdf

Wilson, M. L., C. Boesch, B. Fruth, T. Furuichi, I. C. Gilby, C. Hashimoto, C. Hobaiter, G. Hohman, N. Itoh, K. Koops, J. Lloyd, T. Matsuzawa, J. C. Mitani, D. C. Mjungu, D. Morgan, R. Mundry, M. N. Muller, M. Nakamura, J. D. Pruetz, A. E. Pusey, J. Riedel, C. Sanz, A. M. Schel, N. Simmons, M. Waller, D. P. Watts, F. J. White, R. M. Wittig, K. Zuberbühler and R. W. Wrangham (2014). “Lethal aggression in Pan is better explained by adaptive strategies than human impacts.” Nature 513: 414-417.

Wilson, M. L., S. M. Kahlenberg, M. T. Wells and R. W. Wrangham (2012). “Ecological and social factors affect the occurrence and outcomes of intergroup encounters in chimpanzees.” Animal Behaviour 83(1): 277-291. get pdf

Wilson, M. L., W. Wallauer and A. E. Pusey (2004). “New cases of intergroup violence among chimpanzees in Gombe National Park, Tanzania.” International Journal of Primatology 25(3): 523-549. get pdf

Wrangham, R. (1974). “Artificial feeding of chimpanzees and baboons in their natural habitat.” Animal Behaviour 22: 83-93.

Wrangham, R. W. (1999). “The evolution of coalitionary killing.” Yearbook of Physical Anthropology 42: 1-30.

[1] We invited all co-authors of our original paper to contribute to this response. All of those who responded to our invitation provided feedback and asked to be included as co-authors. Most (or perhaps all) of those who have not yet responded to this request are currently in the field with limited access to email. Not being included on this list, therefore, does not necessarily imply any disagreement with the contents of this response.

thoughts on primates, people, and evolution