Category Archives: Field Sites

Do Chimpanzees Have Dialects?

I grew up speaking English, first in Minnesota, then in central Illinois. On visits back to Minnesota, friends teased me for having a “southern” accent, like when I described a gar fish as looking “right like an alligator.” I encountered other varieties of English when we moved to Indiana — twangier than the downstate Illinois drawl — and when I went to college in Chicago. But these varieties of American English paled in comparison to what I encountered in Britain, when I spent a year as an exchange student at Cambridge University. As a fan of British television shows (Monty Python, Doctor Who, David Attenborough) and music (the Beatles, Pink Floyd), I expected to understand what people were saying. It turned out to be much trickier than I expected. Instead of the Received Pronunciation of BBC broadcasts, I encountered rapid speech with unfamiliar slang (“naff,” “grotty,” “phoar!”), new vocabulary words (“bog,” “crisps,” “snog”), expressions (“over the top,” “get off with,” “taking the mickey”), with consonants often ghosted as glottal stops. And there wasn’t just one variety to learn. People from different cities, regions, islands and social classes all spoke differently. Chris from Birmingham (“Brum”) spoke in a rapid series of unintelligible words and knowing looks that often left me completely baffled. 

Different varieties of languages – dialects – likely emerge as an inevitable consequence of cultural evolution. People learn their home language from their parents, but they don’t learn it exactly the same. They add new words and phrases and ways of speaking that they pick up from their friends, and in the modern world, other sources like books, television, and the internet. As these differences accumulate, ways of speaking diverge. Descent with modification leads to the formation of new languages, just as in biology it produces new species.

Do other animals have dialects? Peter Marler, a pioneer in the study of animal behavior, demonstrated that some animals do. Songbirds have two main categories of calls: short, simple calls for everyday use, such as predator alarm calls, and more elaborate songs, mostly used during the mating season. Birds sing to defend territory, attract mates, and once mated, to communicate with their partner. Over the course of a long career, Marler conducted an elegant series of field studies and laboratory experiments, demonstrating that in species such as white-crowned sparrows, songs must be learned. A sparrow raised in isolation produces abnormal songs, but if he hears recordings of songs while growing up, he produces a normal song. Because sparrows learn their songs, local variants emerge and gradually change over time, producing regional dialects (Marler, 1970). (Here’s a video describing recent work on dialects in white-throated sparrows.)

Subsequent studies found evidence of such ability to modify calls — vocal learning — in some other species. Humpback whales, for example, sing long, complicated, haunting songs during their mating season. Like in sparrows, males do most of the singing. Whale songs vary not just by region, but also by year. In a given year in Hawaiian waters, male humpbacks sing songs that closely resemble one another, but which differ from what the whales are singing off the coast of Australia — and which also differ from last year’s favorite styles in Hawaii (Mercado et al., 2004). 

Do species more closely related to humans, such as chimpanzees, show any evidence of vocal learning and dialects?

Marler pioneered the study of primate communication as well as birdsong. He visited Gombe National Park, Tanzania, in 1967, where he carried out the first modern field study of chimpanzee vocal communication. Based on his recordings from Gombe, Marler identified a set of 13 basic calls for chimpanzees. He also found that chimpanzee calls generally resembled those of gorillas (Marler, 1976). The similarity of calls among these apes suggests they are mainly under genetic control, rather than learned. However, John Mitani, working as a post-doctoral researcher with Marler, found some evidence for dialects in chimpanzee pant-hoot calls (Mitani et al., 1992). 

When Jane Goodall gives public talks, she often begins by giving a pant-hoot: a loud call that begins with soft hoos, followed by grunts, barks or screams, and often ends with grunts again. (Jane usually leaves out the screams, though, as she thinks those sound too aggressive.)

Spectrogram of chimpanzee pant-hoot call, from Desai et al. (2022)

Pant-hoots are loud, and enable chimpanzees to communicate over long distances through the forest. Mitani recorded pant-hoots from chimpanzees at Mahale Mountains, some 160 km south of Gombe, and compared them to Marler’s recordings of pant-hoots from Gombe. Analysis revealed some subtle differences: Mahale chimpanzees produced shorter grunts at a faster rate than Gombe chimpanzees, and produced pant-hoots with higher-pitched screams (Mitani et al., 1992). Later studies reported similar geographic variation in calls among groups of captive chimpanzees (Marshall et al., 1999), between chimpanzees in Uganda and Tanzania (Arcadi et al., 1996), and among communities of chimpanzees at Taï Forest in Côte d’Ivoire (Crockford et al., 2004). 

The idea that chimpanzees have distinct pant-hoot calls is an intriguing one. Moreover, the study led by Cathy Crockford (2004) reported that neighboring communities differed from one another more than they did from more distant communities. This suggested that chimpanzees produced calls that announced their community membership to other chimpanzees. This would make sense, given the hostile relations between chimp communities. A pant-hoot call would function like a sports team uniform or national flag, announcing the caller as a member of team Mitumba or Kasekela. Perhaps vocal learning evolved in our own ancestors in response to selection pressure from intergroup aggression?

As a graduate student, I conducted a series of playback experiments with chimpanzees in Kibale National Park, Uganda (Wilson et al., 2001). I used recordings that Mitani had made of chimpanzees from Mahale. In each experiment, I played back a single pant-hoot from a Mahale chimp from a speaker hidden hundreds of meters from Kibale chimpanzees. This single simulated intruder provoked an immediate and striking response. If the listening party consisted only of females, they silently climbed down from the tree where they had been resting or feeding and moved off in the opposite direction. If one or two males heard the call, they stayed silent, and either stayed in place, looking towards the source of the call, or slowly approached the speaker. If three or more males heard the call, though, they immediately gave a loud vocal response and rapidly approached the speaker, as if they were looking for an intruder to attack. So chimpanzees can clearly tell friend from foe by their voice. But were they responding to differences in dialect? Or just differences in familiar versus unfamiliar individuals?

As Mitani and his team continued to analyze calls from different chimpanzee sites, though, they dialed back on claims of dialects. When Mitani began recording calls at Kibale, he found that chimpanzees in Kibale do produce pant-hoots with build-up elements, despite the previous report that they don’t (Mitani et al., 1999). They also found that much of the variation in acoustic structure occurred within individuals, rather than between communities. 

So, do chimpanzees have dialects or not? In an effort to answer this question, I worked with my graduate student, Nisarg Desai, and a team of Tanzanian field assistants to record and analyze chimpanzee vocalizations. Team members followed chimpanzees through the forest, carrying a hand-held “shotgun” microphone and a digital recorder, recording as many calls from each individual as possible.

Three researchers at Gombe National Park, Tanzania
The Chimpanzee Dialects Project team at Gombe: Nasibu Madubmi, Hashimu Salala, and Nisarg Desai.

When Nisarg analyzed the data, he found that individuals varied a lot in the calls, but community membership explained little of the variation between the calls. Analyzing calls that Pawel Fedurek had recorded in Kibale, Nisarg again found lots of variation among individuals, but no clear geographical variation (Desai et al., 2022)

Acoustic analyses from Desai et al (2022). Pant-hoots from the different communities showed lots of overlap in their acoustic features.

Based on Nisarg’s findings, and on the subtle differences reported from other studies, I’m inclined to think that chimpanzees do not have dialects after all. Chimpanzees and other apes may yet prove to have some limited capacity for vocal learning. But any such capacities in nonhuman apes pale in comparison, not just to humans, but also to many birds and whales in terms of vocal learning. This aspect of language seems to have emerged only after our ancestors diverged from the Pan-human ancestor.

Figure showing results from acoustic analysis of chimpanzee pant-hoot calls.
Most of the variation in acoustic features occurred among individuals within communities, rather than between communities. (Desai et al., 2022)

All of this raises questions about what promotes vocal learning in other species, and whether similar factors promoted vocal learning in human ancestors. To be continued!

Researcher with chimpanzees
Nisarg Desai with chimpanzees Sandi, Ferdinand, and Siri at Gombe National Park, Tanzania


Arcadi, A. C. (1996). Phrase structure of wild chimpanzee pant hoots: patterns of production and interpopulation variability. American Journal of Primatology, 39(3), 159-178.

Crockford, C., Herbinger, I., Vigilant, L., & Boesch, C. (2004). Wild chimpanzees produce group‐specific calls: a case for vocal learning?. Ethology, 110(3), 221-243.

Desai, N. P., Fedurek, P., Slocombe, K. E., & Wilson, M. L. (2022). Chimpanzee pant‐hoots encode individual information more reliably than group differences. American Journal of Primatology, e23430.

Marler, P. (1970). Birdsong and speech development: Could there be parallels? There may be basic rules governing vocal learning to which many species conform, including man. American scientist, 58(6), 669-673.

Marler, P. (1976). Social organization, communication and graded signals: the chimpanzee and the. Growing Points Ethology, 239.

Marshall, A. J., Wrangham, R. W., & Arcadi, A. C. (1999). Does learning affect the structure of vocalizations in chimpanzees?. Animal behaviour58(4), 825-830.

Mercado, E., Herman, L.M. & Pack, A.A. Song copying by humpback whales: themes and variations. Anim Cogn 8, 93–102 (2005).

Mitani, J. C., Hasegawa, T., Gros‐Louis, J., Marler, P., & Byrne, R. (1992). Dialects in wild chimpanzees?. American Journal of Primatology27(4), 233-243.

Mitani, J. C., Hunley, K. L., & Murdoch, M. E. (1999). Geographic variation in the calls of wild chimpanzees: a reassessment. American Journal of Primatology: Official Journal of the American Society of Primatologists, 47(2), 133-151.

Wilson, M. L., Hauser, M. D., Wrangham, R. W. 2001. Does participation in intergroup conflict depend on numerical assessment, range location, or rank for wild chimpanzees? Animal Behaviour 61(6): 1203-1216.

Filoha Birds

Some years ago, I learned that one of the keys to happiness is birding. I was serving as a lecturer on a tour of parks and game reserves of southern Tanzania. We went to some amazing places — but the people devoted to spotting mammals were often unhappy. The woman who desperately wanted to see a leopard was deeply disappointed, as we didn’t see one. I told her I had spent years doing fieldwork in Africa but had only seen a leopard once; this provided little consolation for her. She had paid lots of money for this trip, and she wanted to see a leopard. At Mahale, the tour split into two groups, one of which had luck finding chimpanzees, while the other group didn’t. The people who didn’t see chimpanzees were bitterly disappointed and spent the rest of the trip drinking deeper into the supply of white wine. At Selous, a vast and magnificent game reserve, people complained, “We didn’t see anything today! Just zebras and giraffes. Oh, and hippos and elephants.” For the people focused on seeing mammals, seeing herds of amazing megafauna quickly became routine, shadowed by their unsatisfied desire to see something even more charismatic.

The birders, however, were happy everywhere we went. Even at the end of the trip, at the Dar-es-Salaam airport, one cheerful white-haired birder was delighted to see house sparrows, which boosted his total count of bird species seen on this trip to over 100.

As the Buddha said:

If you desire those desires that will be satisfied, you will be satisfied; if you desire those desires which will be frustrated, you will be frustrated.

Surprisingly, few people seem to be aware of birds. People don’t look up. While walking across the Washington Avenue Bridge between the West and East Bank campuses of the University of Minnesota, I have often seen a bald eagle soaring overhead – and crowds of people walking underneath the eagle, oblivious to it. The key to happiness is right there, and yet people ignore it.

Birds are more diverse than mammals, in terms of number of species: perhaps 10,000 birds, compared to about 5,000 mammals. Birds are mostly active during the day, when they are easy to see, whereas most mammals are active by night. Nearly 60% of all mammal species are either rodents (~2000 species) or bats (~925 species), which are mostly nocturnal. In a city like Minneapolis, most of the resident mammals are either nocturnal or crepuscular. In my urban neighborhood near the Mississippi River, we have many mammals: bats, shrews, mice, chipmunks, squirrels, rabbits,  woodchucks, skunks, raccoons, opossums, and even foxes, coyotes, beavers and deer. Despite this diversity, most of these mammals stay hidden  during the day. Birds, in contrast, are more conspicuous: often brightly colored and active during daylight hours.

Why do birds rule the day, while mammals rule the night? Because birds are dinosaurs. During the Mesozoic, when dinosaurs ruled the world, mammals were tiny things, cowering in the trees or squirreled away in their burrows, daring to come out only at night.

Our perception of dinosaurs is distorted because only the flying dinosaurs survived the Chicxulub meteor impact in the Yucatán 66 million years ago. It’s like if we lived in an alternate universe where the only mammals that survived on earth were bats. (New Zealand was like this before human settlers arrived; it was a land dominated by giant flightless birds, with no land mammals except for bats.) Then if we found fossils of elephants and hippos we would be amazed at these giant creatures of the past and find it hard to believe they were at all related to the little flitting bats.

After the Chicxulub impact ruined the world for flightless dinosaurs , some mammals gradually evolved daytime habits. But most mammals remain creatures of the night and twilight. Nocturnal habits mark mammals as a group. Ancestral mammals lost the full color vision of their fishy ancestors. Most fish, amphibians, reptiles and birds have four types of color receptor (cone cells) in their retinas, whereas most mammals have only one or two kinds of cone cell. With the value of vision reduced by darkness, mammals rely more on scent and touch, their faces marked by moist noises, large nasal passages, and sensory hairs. In contrast, birds, like their dinosaur ancestors, continue to rule the day.

Primates are among the few mammalian groups that are mainly active by day. Some primates, such as bushbabies and many lemurs, retain the primitive mammalian traits: moist noses, 2-cone color vision, and nocturnal habits. But other major primate groups have evolved dry noses (part of a reduced reliance on smell), 3-cone color vision, and daytime habits. They can afford to do this because, like tree squirrels, they rely on the safety of trees to protect them from predators. (Even in trees, though, primates still have to worry about predatory dinosaurs. Crowned hawk eagles in Africa kill monkeys as large as adult red colobus monkeys. The Taung child, the first fossil hominin discovered in Africa, was killed and eaten by an eagle.)

One of the great pleasures of visiting Filoha was the abundance of birds.

The mammal fauna of Awash National Park has been severely depleted by hunting and by competition with pastoralists. There are no more elephants or rhinoceroses. Larger antelope are scarce or shy, though I glimpsed a lesser kudu bounding across the road, and from time to time saw a dik-dik scampering through the brush off to the side of the road: beautiful tiny little fairy antelope. Because so many cattle, sheep, goats and camels graze in the park, food is scarce for other herbivores. And because of the people herding the livestock, most larger mammals stay hidden during the day. But the birds are there.

Because the trees are small and sparse, the birds are easy to see. I saw Hoopoes several times, though never when I had my camera handy. These are lovely brown birds with elegant crests. White-headed Buffalo Weavers emerged frequently from the acacia trees.

White Headed Buffalo Weaver
White Headed Buffalo Weaver

White Headed Buffalo Weaver in Flight
White Headed Buffalo Weaver in Flight

Weavers as a group are fascinating birds. Living up to their name, they build tightly woven nests in trees, with a characteristic nest shape for each species. The nests commonly have a snail-like shape to deter predators: an opening at the bottom, leading around a corner to a nest cavity. (Though even these clever nests are not perfect protection from predators: I have seen redtailed monkeys and harrier hawks reach into these nests and pluck out baby birds.)

Weaver bird nest
Weaver bird nest

2015-08-11 Redbilled Hornbill
Redbilled Hornbill

2015-08-11 Malachite kingfishers A
Malachite Kingfishers







We saw Hornbills frequently, and caught one good glimpse of a pair of brilliantly colored little Malachite Kingfishers.








Lilac Breasted Rollers — which have almost more colors than really seems fair for any single bird— and irridescent Longtailed Starlings hung out close to camp. In America, starlings are kind of boring blackish birds, noisy and superabundant invasive birds from Europe, but in Africa, starlings are gorgeous and glossy.

Longtailed Starling and Lilac Breasted Roller
Longtailed Starling and Lilac Breasted Roller






The most spectacular place for birds, though, was in the wetland near Filoha camp.

Gray Heron, African Spoonbill and Warthogs
Gray Heron, African Spoonbill and Warthogs





The research camp is located at the foot of a cliff, which is the edge of a lava flow from several hundred years ago. Awash is located in the Rift Valley, where East Africa is slowly separating from the rest of Africa. Eventually, East Africa will become one or more large islands off the coast of Africa, like Madagascar is today. The Rift Valley is a place where crust is oozing up from below, filling in the gap between the separating plates. Along the entire length of the rift, earthquakes are common; some of the buildings at Filoha have cracked and crumbled cement foundations from a recent tremor. Awash is dominated by a great volcano, Mount Fentale. And much of the park is covered with lava flows of varying ages.

Fentale Mountain
Fentale Mountain







Filoha means hot spring, and the hot springs are the main attraction that brings tourists and local people to this part of the park. Local people believe the hot springs have magical powers which promote healing. Given that the average temperature in the park is already suffocatingly hot, it seems a bit excessive to add hot springs. One source stated the temperature of the springs as 43.5 ºC. Given that air temperatures can rise over 45ºC, at such times the hot springs must seem refreshingly cool.

The researchers bathe in the hot springs, using a little waterfall at the edge of the cliff. They can only do this on days that they get back from the field early enough, though; after dusk the danger from lions and hyenas grows too great. The same waterfall provides the major source of drinking water. The hot springs empty out onto a green expanse of mudflats, streams and wetlands. Padding along the mudflats and wading in the pools are Sacred Ibises, Hadaba Ibises, Spurwing Plovers, African Spoonbills, Grey Herons, Egrets and others.

Spurwinged Plover
Spurwinged Plover









Crocodiles lurk in the shallow pools, hunting fish. So nice to see these ancient cousins of birds – fellow Archosaurs – just meters away (but at a seemingly safe remove).

African Spoonbill with crocodile lurking in background.
African Spoonbill with crocodile lurking in background.





The path to the hot spring pool leads across an expanse of mudflats with real quicksand. The quicksand looks like a patch of bare earth, but if you hit it with a stick it quivers like Jello. Vehicles occasionally get stuck in the quicksand, as do people. But the wetland birds, with their long dinosaur toes and light bodies, seem to be safe.

2015-08-15 Egret flying white






It was deeply satisfying to be among animals that figure so prominently in the art of ancient Egypt: Sacred Ibises, crocodiles, and (coming up in the next post!) Hamadryas baboons.

2015-08 Sacred Ibis
Sacred Ibis









Works Cited

Further Dialogues of the Buddha, Vol. II, p. 237. Quoted in Philosophy of the Buddha by Archie J. Bahm (1958). Harper & Brothers.

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
Some Amharic letters (from

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.

Twins and Cousins

Gombe is a special site for many reasons. Among them: It is the first site where wild chimpanzees were observed to make and use tools. It is also the only wild site where twin chimpanzees have survived to adulthood. On my recent visit to Gombe, I had the good fortune to see the twins and their daughters making and using tools to fish for termites.

Back in 2002, I remember following a large group of chimps in the Kasekela community, on the narrow trail climbing the steep path above Kakombe Valley, heading south to Mkenke Valley. It was Mabungo season and the chimps were feasting on fruits from the different kinds of Mabungo vines, especially Mabungo Makubwa (Big Mabungo) and Mabungo Madogo (Little Mabungo). The chimps traveled single file down the narrow trail. In the midst of the rainy season, everything was lush, green, and wet. The last chimp in the line was Gremlin, carrying her twins, Golden and Glitter, on her back. Sometimes their older sister Gaia would help mom by carrying one of the little twins. Gaia’s help is probably one reason that Golden and Glitter survived to adulthood — the only known pair of wild chimp twins known to have done so. Even with this help, though, the twins slowed Gremlin down. Being new to Gombe, struggling with the hikes up and down the hills, I was quite happy walking behind them, grateful for a chance to rest a little while watching these little girls play.

Amri collecting data on the twins, Gitter and Golden, and their babies, Gossamer and Glamour.
Amri collecting data on the twins, Gitter and Golden, and their babies, Gossamer and Glamour.

Now Golden and Glitter are all grown up.  Female chimpanzees usually leave the group of their birth and join a new one, to avoid mating with their brothers, uncles, fathers and such. At Gombe, though, about half of the Kasekela females stay in their natal group, probably because the dispersal options are limited: Mitumba is small and crowded, while Kalande is big but less forested (so less food) and has too few adult males.  So Golden and Glitter have stayed in Kasekela, as did their mother Gremlin.

We don’t know if Gremlin’s mother Melissa was born in Kasekela or if she immigrated from elsewhere. But now that Golden and Glitter have babies of their own (Glamour and Gossamer), we have four generations of G-family girls in one community. Their older sister Gaia has also stayed in Kasekela. When all the G-family moms and babies get together, it’s more like a baboon matriline than a typical chimpanzee group of unrelated females. This concentration of female kin might have some interesting implications for social behavior. Maybe all these related females will gang up on other females to control access to the best home ranges? They do seem very well established in Kakombe Valley, the best, most productive valley in Gombe in terms of chimpanzee foods.

Glamour, who just like her mother Golden, has a white spot on the top of her head. (11 June 2014)
Glamour, who just like her mother Golden, has a white spot on the top of her head. (11 June 2014)

This June, in between visits to the Kalande and Mitumba communities, I was able to spend some time following the twins and their daughters.

They spent much of the morning fishing for termites. Usually there’s more termite fishing in the wet season than this time of year, the early dry season, but perhaps the recent rains had softened up the mounds enough to make it easier for the chimps to stick in their termite fishing tools: wands made of grass or sticks, stripped of leaves to make slender probes.

Golden eating termites from her fishing wand.

Golden standing quadrupedally and holding her wand in her mouth. (11 June 2014)
Golden standing quadrupedally and holding her wand in her mouth.
(11 June 2014)

Jane Goodall’s discovery that chimpanzees make and use tools to fish for termites was one of the key findings that made Jane and Gombe famous. In The Descent of Man, Darwin argued that the making and using of tools originated after the evolution of bipedalism: walking on two legs freed the hands for manipulation, rather than transportation. It was therefore a surprising discovery that these knuckle-walking forest apes regularly used their hands, not just for walking and climbing, but also for making and using what has turned out to be a large variety of tools.

Tools increase access to important foods that would not otherwisebe available. Termites, for example, are rich in fat and protein, nutrients that are important but not well supplied by the mainstay of chimpanzee diet, ripe fruit.

Golden eating termites from her hand. (11 June 2014)
Golden eating termites from her hand.
(11 June 2014)

Tool use also increases the value of social learning. Termite fishing is a skill that takes years to learn properly, and kids mainly learn how to termite fish from watching their moms. As Elizabeth Lonsdorf elegantly showed with her studies of termite fishing at Gombe (in which Gremlin and the twins figured prominently), girls learn to termite fish faster than boys, probably because boys are too busy playing rough-and-tumble games.

Once cultural learning is established, a whole range of new subsistence strategies can be acquired that any one individual would never think to invent on their own.

Darwin was probably right that being bipedal helps with making and using tools. Chimpanzee hands are long, with curved fingers and short, weak thumbs. Australopith hands are much better suited for both the precision grip and the power grip. They must have had a much broader range of tools than chimpanzees: sticks for digging food and hitting rivals, stones for smashing food and throwing at enemies. But the discovery of tool use and material culture in chimpanzees suggests that these practices may have already been present in our common ancestor with chimpanzees, predating the origin of bipedalism — and perhaps providing increased selective advantages for individuals in those populations that first started standing bipedally a bit more than usual.

Imani standing bipedal to feed. (10 June 2014)
Imani standing bipedal to feed.
(10 June 2014)


On Thursday, 12 June, Deus, Rebecca and I visited the Mitumba community in the North of Gombe.

Gombe is one of the few sites where researchers can study neighboring chimpanzee communities. At most sites, researchers focus on a single study community, and don’t know very much about the neighbors. This was the case at Gombe for many years, but since the Mitumba chimpanzees were habitatuated in the 1990s, we have been able to follow chimpanzees from two communities simultaneously. And now, with monitoring of the Kalande chimpanzees, we can track the movements of nearly every chimpanzee in the park.

The prospect of studying intergroup interactions from both sides of the event is what led me to start working at Gombe, and has been a focus of my research ever since. Deus has played a big part in this, as he collected data on the Mitumba chimpanzees, first as a research assistant on the intergroup relations project, and then as a PhD student.

When I first started working at Gombe, we worried that males from the larger, more powerful Kasekela community would kill the remaining males from Mitumba and take over their range. And sure enough, soon after I started working at Gombe, the young male Rusambo was found dead, with severe wounds, the day after Kasekela males traveled deep into Mitumba’s range (Wilson et al., 2004).

Edgar keeping a close eye on Flirt
Edgar keeping a close eye on Flirt

However, since then, the Mitumba males have held on, and even seem to have expanded their range a bit. And while intergroup incursions from Kasekela have continued, including the killing of the young infant Andromeda (Wilson, 2013),  it is the Mitumba males who have proved a greater threat to themselves. Mitumba males Edgar and Rudi killed their former alpha male, Vincent, in 2004. Soon after, the young male Ebony was found dead. Since then, Edgar and Rudi have fought bitterly and Rudi has disappeared. Edgar seems determined to keep Mitumba for himself, as if he were a gorilla silverback.

When we arrived in Mitumba, we walked up the steep, narrow valley of Mitumba stream. Gnarled old Mgwiza trees grow along the stream banks, and Lusieno trees tower overhead.


Flirt climbing down from her feeding tree.
Flirt climbing down from her feeding tree.

We found chimps close to the stream. Edgar followed Flirt closely. She had a full swelling and he clearly wanted to keep her all to himself. Flirt is one of Fifi’s daughters. She was born and raised in Kasekela. She was orphaned when her mother died in 2004, but managed to survive, spending much of her time with older brother Frodo. Flirt is one of the very few chimpanzees I ever saw Frodo groom.

After Flirt reached sexual maturity, she did what female chimpanzees usually do:  transferred to a new community. With Edgar showing so much interest in her, maybe she will conceive an infant soon.

Young male Apple followed them from a distance.  Apple is one of the2014-06-12 Apple sitting in tree A rising generation of Mitumba males, along with Kocha and Ramba. If these boys survive to maturity, then Mitumba may have a chance at keeping Kasekela at bay and maintaining Mitumba as a viable community. But with Edgar’s track record of attacking other males, maybe he won’t let these young competitors survive. If Edgar continues killing all the young males, his line may end in a Pyrrhic victory: eliminating not only his competitors, but his only allies against the mighty Kasekelans.

After coming down from the trees, the Mitumba chimpanzees soon climbed up the steep slide of the hill, giving us a chance to experience some classic Mitumba chimp viewing: crawling on hands and knees through vine tangle.



On June 10th, I traveled to the south of Gombe to visit the range of the little-known Kalande community of chimpanzees.

Map of Gombe National Park and chimpanzee ranges (from Rudicell et al., 2010)
Map of Gombe National Park and chimpanzee ranges (from Rudicell et al., 2010)

The Kalande community is one of three chimpanzee communities at Gombe.

The most famous, most intensively studied chimpanzees live in the Kasekela community in the center of the park. These are the chimpanzees that Jane Goodall has studied since 1960. They have the biggest range and the most members of the park’s three communities.

To the north of Kasekela live the Mitumba chimpanzees. This is a smaller community, which Deus Mjungu studied for his PhD research. The Mitumba community has fewer chimpanzees than Kasekela, but is still vigorous. They have a small range, but it includes excellent chimpanzee habitat with lots of food trees.

To the south is the Kalande community (also known as Bwavi). Most of the Kalande community’s range is grassland and woodland, with narrow strips of forest along the stream valleys. We know less about the Kalande chimpanzees than any of the others in Gombe. For the most part, these chimpanzees are still unhabituated, meaning they fear people. Researchers can follow the Kasekela and Mitumba chimpanzees around all day long, but they are lucky to get even fleeting glimpses of Kalande chimpanzees.

We aren’t even completely sure how many chimpanzees live in Kalande. Based on sightings and samples of genetically distinct individuals, there seem to be at least 9 chimpanzees in Kalande, but we don’t know for sure.

Skull from a male chimpanzee found dying in Kalande in 1994 or 1995.
Skull from a male chimpanzee found dying in Kalande in 1994 or 1995.

A small team of researchers monitor the Kalande chimpanzees. They collect fecal samples for genetic analysis, which enables us to keep track of individuals, even when we don’t know what they look like. Kalande has the highest rate of infection with the virus SIVcpz, which likely contributed to the decline of this community (Rudicell et al., 2010). Many females have left Kalande for other communities, both as part of the natural emigration process (females usually leave to join a new community when they are sexually mature), and because as Kalande declined, it eventually came to have too few males. Females seem to prefer living in communities with many males, both because many males are better able to defend the feeding territories that females need to survive and raise their offspring, and because females need unrelated males as mating partners. As the number of adult males in Kalande dropped down to one, or perhaps even zero, some Kalande females left for good, while others seem to have kept their Kalande home base, but visit Kasekela for mating.

Kat and Kazi, photographed when visiting Kasekela (20 April 2006)
Kat and Kazi, photographed when visiting Kasekela (20 April 2006)

Kati, for example, is a Kalande resident who has probably lived there since 1998.  Based on genetic data, we think she is the daughter of Patti who was known as Tita when she was younger. Since 2006, Kati has been making occasional visits to Kasekela. I saw her with her young son Kazi on one of these early visits. Of the Kalande chimps, Kati seems to fear people the least, which would make since if she grew up in Kasekela.

Deus and I took the boat to Kalande, where we met Ashaabu, one of the new Kalande research assistants. Ashaabu got his start working as a village Forest Monitor for his village’s forest reserve (part of the Greater Gombe Ecosystem project). Before going into the forest, we talked with Ashaabu for a while about which chimpanzees he has been seeing.

Kazi, who was just a little boy back in 2006, now seems to be the alpha male of Kalande, even though he is just a gawky adolescent. Based on how old Kazi looked back in 2006, I think he must be at least 12 years old now. Ashaabu says Kazi is around the size of the Kasekela male Fundi, who is about 14. The old male Renadi (or Leonard) hasn’t been seen for a number of years now, and I suppose must be dead. There might be another adolescent male, Pamera, but we don’t know for sure if he is still alive. Ashaabu has regularly seen Kati, Kazai, Katarina (Kati’s new baby), a big female without an infant, an adolescent female (who I think might be Pairott), and another young female around Kazi’s size. (Perhaps this is really Pamera? Might be hard to tell he’s a male if he’s still young and seen only briefly from a distance.) Ashaabu also mentioned Obedina, a female who had a big belly last year who might also have a new baby now.

After talking, we hiked into the forest, climbing a steep rocky path into Nyamagoma valley. Nyamagoma is the southernmost valley of the park, just north of Kazinga village. The path wound through an open woodland with a view of the lake below.

Ashaabu collecting Msongati fruits.
Ashaabu collecting Msongati fruits.

Along the way, we collected fruits and leaves for the isotope and nutrition projects. Given that Kalande has so much woodland, it will be interesting to see if the Kalande chimpanzees, or their foods, differ isotopically at all from those in Kasekela.

Ashaabu and Deus below a chimp nest.
Ashaabu and Deus below a chimp nest.

We followed the path down towards Nyamagoma Stream, where tall trees grew, shading the steep valley in green light. We didn’t see any chimpanzees, but we did see a number of nests. Chimpanzees build a new nest (or bed) in trees each night to sleep safely out of reach of any predators that might be lurking about. We found one cluster with five fresh nests, suggesting that up to seven chimpanzees might have slept there (if the group included Kati and Obedina and their new babies). It was encouraging to see so many fresh signs of chimpanzees using this valley. The Kalande community is still hanging in there, and perhaps they might recover, if the Kasekela males don’t catch Kazi and finish him off.

Ashaabu taking data on his tablet.
Ashaabu taking data on his tablet.

Ashaabu carried with him the tablet computer he had used as a Forest Monitor. He used the tablet to take pictures of the nests and enter the data, including GPS locations of the nests. It was quite stunning for me to think each of the villages around Gombe now has its own Forest Monitors, collecting data like this on their own village forest reserves, and loading it up regularly into the Cloud.









Director of Chimpanzee Research for Gombe Stream Research Centre.





Isotopes and Isoptera

My main goal in visiting Gombe this trip was helping my graduate student, Rebecca Slepkov Nockerts, get started with her project on the stable isotope ecology of chimpanzees and baboons at Gombe.

Over the past couple of decades, stable isotope studies have revolutionized the study of the diets of human ancestors.

Isotopes are variants of chemical elements that differ only in the number of neutrons. For example, carbon has three naturally occurring isotopes, of which Carbon-12 (12C) is the most common. All carbon atoms have 6 protons – that’s what makes them carbon atoms, and not some other element. 12C has 6 protons and 6 neutrons, and is stable – each atom can last for billions of years. Carbon-14 (14C) is a radioactive isotope of carbon. It has 6 protons and 8 neutrons – which makes it unstable. It gradually decays, turning into Nitrogen-14 while spitting off an electron and an electron anti-neutrino. By geological standards, 14C  decays relatively quickly, making it useful for dating objects containing carbon that are up to about 60,000 years old.

The third naturally occurring isotope of carbon, 13C, has 6 protons and 7 neutrons, and is stable, though  much less common than 12C. For the most part, chemical reactions  involve interactions among electrons, and to some extent protons. Neutrons don’t get involved. As a result. 13C behaves chemically almost exactly like 12C. However, in some reactions, the slightly different mass of the heavier isotopes can make a difference. For example, in photosynthesis, molecules containing 13C move more slowly, because they are heavier, and end up in different proportions in the final product.

As it turns out, several different major groups of plants use different mechanisms of photosynthesis, which produce distinct isotopic signatures. Especially important in paleoanthropology are C3 plants (most plants, including most forest species) and C4 plants (certain plants adapted to hot dry climates, including many tropical grasses and sedges).

Unfortunately, all of these different numbered C’s quickly get very confusing! But the main thing to remember is that C3 = forest, C4=grass.  Chimpanzees mainly eat C3 forest plants. Even in dry woodlands, chimpanzees eat mainly forest plants: fruit, seeds, flowers and leaves from trees, vines and shrubs growing along rivers and streams. In contrast, baboons eat more C4 plants – especially grass seeds and corms. Similarly, stable isotope studies of fossils have found that early hominins ate mainly Cplants (and/or animals that ate Cplants), whereas later hominins at more C4 plants (and/or animals that ate C4 plants).

However, all of these inferences about hominin diet depend on some assumptions about how different tissues reflect diet. Unfortunately, studies comparing hominin isotope signatures to those of living species usually use different tissues. Studies of fossils usually use tooth enamel, which is extremely stable and thus is thought to maintain a good record of the living animal’s isotope signature for millions of years after death. Studies of living primates, however, usually use tissues that are easier to obtain, such as hair and feces, because it is hard to get tooth enamel from living animals (which are generally busy using their teeth). We therefore don’t know nearly enough about how diet translates to isotope signatures across these different tissues in living species. This is what Rebecca plans to find out.

Freud eating termites  (02 Nov 2006)
Freud eating termites
(02 Nov 2006)

The long-term study of chimpanzees and baboons at Gombe brings together the key pieces needed for this study: expertise in identifying and collecting the important food species, long-term records on diet, and skeletons from known individuals. For example, we have a lifetime of data on chimpanzees like Freud, pictured here in November, 2006 eating termites.

Rebecca and Deus examining the bones of Freud the chimpanzee
Rebecca and Deus examining the bones of Freud the chimpanzee

Freud recently died, at nearly 43 years of age (making him one of the longest lived Gombe males). Thanks to concerted efforts over the years by people at Gombe Stream Research Centre, the skeletons of Freud and many other well known individual chimpanzees and baboons have been preserved. Thanks to a lifetime of data on these individuals, we know a lot about what they have been eating. This comprehensive data on individuals will provide an unparalleled amount of detail for matching up diet to isotope signatures of different tissues.

It is particularly interesting to look at chimpanzees and baboons at Gombe because these two quite similar species differ somewhat in their diets in ways that parallel some differences between early and later hominins: baboons eat more grass than chimpanzees, just as later hominins appear to have eaten more grass (and/or grass-eating animals) than earlier hominins.

Rebecca and baboons collecting grass samples
Rebecca and baboons collecting grass samples

We are working together with Carson Murray and Rob O’Malley, who are conducting a nutritional study of chimpanzees. Both the nutritional study and the isotope study need foods to be collected, so we will work together to collect foods and share samples.

Rob did his PhD work at Gombe, studying insectivory by chimpanzees. Chimpanzees and baboons both eat a wide range of insects at Gombe.

Termites emerging from the nest
Termites emerging from the nest

On our first day in the field, we were lucky to catch an emergence of flying termites (“kumbi kumubi” in Swahili). These members of the infraorder Isoptera are one of the most important insect foods, not only for chimpanzees and baboons, but also many birds, monitor lizards, and even people.

Rebecca and Rob collecting termites.
Rebecca and Rob collecting termites.

We also found a nice column of Dorylus army ants (“siafu” in Swahili).

siafu jaws
Column of army ants showing off their jaws

Army ant soldier biting Rob's thumb.
Army ant soldier biting Rob’s thumb.

From an isotopic perspective, insects like termites and army ants may be interesting mainly for another isotope, Nitrogen, which provides information about where an animal gets its protein from. The higher the animal’s trophic level (the higher it is in the food chain), the more enriched its tissues are in the heavier Nitrogen isotope, 15N. It will be interesting to see whether chimpanzees and baboons at Gombe differ in their Nitrogen isotope signatures, and whether the isotopic signatures of individual chimpanzees relate to how much meat or insect matter they ate while alive.

At the night meeting, Rob and Rebecca explained their projects to the chimpanzee field staff. Rob talked about nutritional differences that he had found between ants and termites. I noted that “even people like to eat termites, right?” The field assistants responded with many people talking at once. The general consensus: “We like to eat termites, yes, but we like locusts even better!”

And I have to agree. Termite sauce with mushrooms is okay but seems a bit buggy to me, whereas fried locusts quite tasty.

Return of the Trees

04 June 2014

Gombe National Park is pretty remote. It is in the northwest corner of Tanzania, on the shores of the world’s longest and second deepest lake, Tanganyika. From the lakeshore at Gombe, you can see the hills of Burundi to the north and the mountains of Congo across the lake. It took me several days of travel, by train, plane and boat, to get to Gombe from our current home in France.

The research station at Gombe is only 22 km (14 miles) north of town, but because Gombe is surrounded by steep hills, you can’t drive there. Instead, we travel by boat, which usually takes 1.5 to 2 hours, depending on the conditions of the lake. The lake is often calm in the morning, but as the air heats up in the afternoon the lake gets choppier, until early evening when (usually) it starts to calm down again.  We left town at 2:00 pm, with a heavily laden boat and rough water.

Loading up Gombe boat






Having been away for two years, the biggest change I noticed was on the hills above the lakeshore villages. When I first visited Gombe in 2001, the hills outside the park were bare. Fields of cassava and beans were planted on slopes that seemed much too steep for agriculture. Red earth showed from erosion scars, including one in Mtanga village where a landslide in January 2001 killed 13 people.

Here’s a picture of Kazinga village, right at the southern boundary of the park, in August, 2005:

Kazinga Ridge 20050809




The park boundary runs along the crest of the hill, and apart from one big green mango on the ridge in the foreground, the trees end at the park. Just about everything on the slopes outside the park has been cut for firewood.

Kazing Ridge 20140604




In contrast, here’s how the same ridge looks now. It’s early dry season so the grass is greener, and thus makes the contrast seem even starker. But even taking this into account, what surprised me was seeing lots of trees on the slopes outside the park. Where the forest used to end abruptly at the park border,  now a blanket of forest drapes over the ridge, extending down towards the village. There aren’t trees everywhere, but even in Gombe the forest cover is intermixed with woodlands and grasslands, depending on the terrain and soil conditions. But that there are any noticeable trees at all outside the park is striking. The Jane Goodall Institute’s reforestation project really seems to be working.

It wasn’t just Kazinga village, either. Passing by many of the lakeshore villages I was struck at the contrast:  steep hills were now blanketed in green trees instead of bare red earth. The photo at the top of this blog post is Kigalye village, which has an especially extensive forest reserve. The trees are coming back.

After I got to Gombe, Lilian Pintea showed me satellite images that confirmed what I had seen from the lake. Not just along the lakeshore, but extending all along the crest of the rift escarpment, trees were coming back. This was the interconnected network of village forest reserves that had been promised in the Greater Gombe Ecoystem project. It really is happening.

The deforestation of the village hills was a classic Tragedy of the Commons. The trees provide many public goods. Their roots hold the soil in place, preventing erosion and landslides and protecting the watershed so important for the streams, the main source of drinking water for the villages. The trees provide wood for cooking fires, furniture, boats, musical instruments and traditional carvings. Many of the trees produce fruit eaten not only by animals such as chimpanzees and baboons, but also by people. Their flowers enable bees to make honey. The leaves of the trees shade the ground, slowing evaporation, helping the soil retain moisture. But because the trees are common property of the village, as the human population grew, people cut the trees faster than they could grow back. Soon the villages suffered the public costs of deforestation: erosion, landslides, fouled drinking water, lack of wood for fuel and lumber, and the disappearance of plants valued for traditional medicine.

In 1994, the Jane Goodall Institute started the Lake Tanganyika Catchment Reforestation and Education Program (TACARE). Twenty years later, with help from many outside sources, including the Nature Conservancy and USAID, the project really does seem to be succeeding.

Will the project be a success in the long term? That really depends on the people living in the villages, and whether, as the years go by, they perceive the forests as providing net benefits to them. There will undoubtedly be cases of human-wildlife conflict. Animals living in the forest reserves may raid crops; and people might hunt the animals. As trees grow bigger, there will be strong temptations to cut the trees with valuable timber, and decisions will need to be made at the village level about how to manage these resources effectively. But seeing these trees growing has given me hope that these are solvable problems.

Solving the origin of a major malaria parasite

A recent study by Beatrice Hahn and colleagues, published in Nature Communications, has solved a major puzzle about the origin of one of the parasites that causes malaria in people worldwide: Plasmodium vivax.

Malaria is one of the world’s deadliest diseases, killing perhaps a million people each year. Most of the people who die from malaria are in Africa, and most of them children. In areas where malaria is common, adults often have a degree of resistance to the disease, but still get sick enough now and then to miss many days of work, suffering from agonizing aches, fevers and chills. Even though most victims are children, many adults die as well, especially when their immune systems are weakened by other infections. Malaria thus has huge economic costs and has been cited as one of the main drags on economic growth for many tropical nations.

Malaria has had a huge impact on human history and evolution. Malaria is one of the major reasons that Africa resisted European colonialism for so long. Europeans visiting Africa died in droves until the discovery that a drug extracted from the bark of the South American cinchona tree, quinine, protects against malaria. Quinine is fairly awful stuff: when I took it to fight a particularly bad malaria infection, it caused vomiting and a painfully loud ringing of the ears. From the mid-20th Century on, more effective anti-malarial drugs have been produced, which have helped many millions of people survive this terrible disease. Visiting and working in the tropics for business, tourism or, say, field primatology, would be a lot more dangerous without these drugs.

Before the discovery of such drugs, and for the many millions of people in poor countries who still don’t have adequate access to them, malaria has served as a powerful source of selection pressure on human populations. Because malaria is so deadly, human populations with long exposure to the disease have evolved a number of different defenses.

Malaria was originally thought to be caused by the “bad air” (Italian: “mala aria) of swamps and marshlands. It is now known to be a group of similar disease caused by several different species of single-celled protozoans from the genus Plasmodium.  Plasmodium falciparum is the most deadly, and the most common in Africa. Plasmodium vivax is more common in Asia.  Because these parasites are different species, and only distantly related, tricks that work to defend against one species of parasite may not work agains the other. 

The most famous  anti-malarial adaptation is sickle-cell disease, which is caused by a single small change to a gene for hemoglobin, the protein that carries oxygen in red blood cells. This change changes the shape of the hemoglobin molecule.

Sickle cells in action. From:
Sickle cells in action. From:

Red blood cells are packed full of hemoglobin, and if cells have only the abnormal hemoglobin, they become abnormally curved (shaped like a sickle or a crescent moon). People with one copy of the gene for sickle-cell disease have higher resistance to Plasmodium falciparum.

People with two copies of the gene, though, have sickle-shaped that cells get stuck going through narrow capillaries, causing all sorts of problems, which shortened life expectancy before the development of modern medical treatments.

Falciparum malaria is such a dangerous  disease that having improved resistance more than offsets the risks of having children whose lives are shortened by inheriting two copies of the gene.

Nonetheless, sickle-cell trait seems a rather clumsy solution to the problem. Kind of like using hand grenades to protect yourself from tigers. The grenades can stop tigers fine, if you can throw them far enough. But if you don’t throw them far enough, they blow up too close and kill you instead. Perhaps sickle-cell is an emergency stop-gap measure that evolved too recently for all the kinks to be worked out yet.

A seemingly better solution to this sort of problem is the Duffy-negative trait, which provides resistance to a different species (Plasmodium vivax), with little apparent cost to people who have the trait.

To understand the tricks that have evolved to defend against different species of Plasmodia, it is useful to know something about the life cycles of these parasites. These life cycles are complex and involves different stages of sexual and asexual reproduction in various organs of different hosts, including the human liver, human red blood cells, mosquito guts, and mosquito salivary glands.

Malaria parasite life cycle. From:
Malaria parasite life cycle. From:

The malaria life cycle is a complicated solution to problems of replication, sex, and dispersal of Plasmodium genes. In most animals that we are familiar with, such as ourselves, individual organisms do the major work of replication, sex and dispersal. As individual organisms, we accomplish these goals by mating, raising kids, and sending them off to college, for example.

Malaria parasites have found ways to outsource most of this work to other organisms. To replicate, they turn human hosts into giant malaria factories, turning red blood cells into production centers that burst, releasing newly produced parasites into the blood stream, infecting new red blood cells, in an exponentially increasing production system that destroys millions of the host’s red blood cells. This is the part of malaria where the human host feels weak and miserable and suffers from alternating fevers and chills.

Most of this replication phase is asexual: making millions of copies of the same thing. This works fine within a single host, but if you want your babies to survive in the cruel and variable outside world, you need to boost their chances by introducing variation into their genes through sex. So towards the end of the cycle, the parasites start making male and female versions, the gametocytes. When mosquitoes suck the blood of an infected host, they suck up these gametocytes, which can then have sex with gametocytes picked up from other hosts. The offspring of the gametocytes then infest the mosquitoes gut, eventually sending sporocytes to the salivary glands, so they get injected into the next person the mosquito bites, starting the cycle over again. The mosquito thus serves as both a malaria parasite dating service and dispersal system. Kind of like college.

Anyway, a key part of the malaria parasites life cycle is getting into the host’s red blood cells. To do that, they use specific proteins on the surface of the blood cell, which serve to transport certain chemical signals across the cell membrane. Plasmodium vivax parasites use one specific kind of protein, the Duffy antigen receptor, to force their way into human red blood cells. In much of Africa, the indigenous people don’t have this receptor. There is thus no way for P. vivax to infect them. People who don’t have the Duffy antigen receptor may suffer some costs, such as increased susceptibility to asthma, but these costs don’t seem to be anywhere near as high as those imposed by sickle-cell trait. And of course they are much less than the costs of dying from malaria.

The African distribution of the Duffy-negative phenotype has been a puzzle, though, because P. vivax is very rare in Africa. The conventional wisdom has been that P. vivax evolved in Asia. How could a parasite that evolved in Asia, and is rare in Africa, select for parasite resistance in Africans? This would be as puzzling as if people in Africa were all born with some sort of inherent immunity to tiger attacks, even though there are no tigers in Africa.

Beatrice Hahn and her team have solved the problem by collecting poop from thousands of apes across Africa. I played a very small part in this study, by overseeing poop collection for a while at Gombe.

Humans are apes, and many diseases that infect humans can also infect other apes, or (like in the case of HIV) originally came from other apes. Malaria is no exception.  On a molecular scale, we are so similar to chimpanzees and gorillas that the  tricks pathogens use for getting into human cells often work for these cells in other apes as well.

Beatrice Hahn’s team has been collecting fecal samples from apes all across Africa as part of a study looking into the origins of HIV-1, the cause of the global AIDS pandemic. It turns out that the same samples, and same molecular methods, that are so useful for studying HIV, are equally useful for studying all sorts of other things that live inside humans and other apes, including other viruses and gut microbes.

Locations of ape study sites
Locations of ape study sites

It turns out that when apes are infected with malaria, they shed some of the malaria DNA out with their poop. Take some poop, put it in a jar of RNAlater, and you can recover all sorts of fascinating genes, including malaria genes.

(When Jimmy Fallon and Justin Timberlake visited Gombe some years ago, they seemed amused by all of our poop collection and made up a song about it: “Poop in a Jar.” Disappointingly, though, they don’t seem to have recorded this one yet.)

It turns out that gorillas and chimpanzees across Africa, but not bonobos, have malaria parasites that genetically are very close to Plasmodium vivax. Compared to the gorilla and chimpanzee parasites, the human vivax is much less genetically diverse. All the human P. vivax belongs to a single branch of the much bushier tree of African ape P. vivax.ncomms4346-f2

It thus looks very clear that P. vivax evolved in Africa, not in Asia, from a plasmodium population that infects other African apes. People must have carried P. vivax with them when dispersing from Africa some 60,000 years ago. More recently, human populations in Africa evolved the Duffy-negative phenotype that proved so effective that P. vivax became extinct in Africa.

This study underscores the importance of evolution in human lives. Evolution happens fast, and human populations continue to evolve in response to our environments. The parasites that infect us evolve even faster. Evolution leaves traces in the genomes of every living organism that can be used to solve innumerable fascinating puzzles. This study highlights the power of molecular methods to answer important questions, especially when combined with field studies.