In college, I took a class taught by Amy Kass called “Human Being and Citizen.” We read and discussed selections from the Bible, Homer, Aristotle, Plato, Shakespeare, Kant, Rousseau, Dostoevsky, and others. After one class, frustrated and confused by the arguments presented in these widely varying texts, I approached Mrs. Kass and asked her,
“What is your foundation for morality?”
She looked at me with a wry smile and a glint in her eye, and said,
“Standing on one foot?”
I understood her point—the impossibility of responding adequately to such a question—but I didn’t get the reference she made until some years later, when I came across a story told in the Talmud (Shabbat 31a) in which a gentile seeking to be converted to Judaism approaches the famed Rabbi Hillel with the challenge,
“Convert me on condition that you teach me the entire Torah while I am standing on one foot.”
Rabbi Hillel responded, “What is hateful to you, do not to your neighbor: that is the whole Torah, while the rest is the commentary thereof; go and learn it.”
Rabbi Hillel lived in Jerusalem during the reign of King Herod, and is thought to have died when Jesus was still a child. Hillel’s version of the Golden Rule would thus belong to a tradition that already existed when, according to Luke, Jesus gave his own version of the Golden Rule in the Sermon on the Mount:
“Do unto others as you would have others do unto you” (Luke 6:31).
Jesus presents the Golden Rule with a positive spin: “do unto others” rather than “do not what is hateful.” Either way, this rule provides a compass for navigating social life, for living well with others. It is so familiar that it seems obvious, even trivial. But it is a radical rule, both in its simplicity, and in its departure from other views of how we should act in the world.
For example, in Plato’s Republic, written around 375 BCE, Thrasymachus proclaims:
“I say that the just is nothing other than the advantage of the stronger” (338c, p. 15).
In other words: “Might makes right.”
Another definition emerges in conversation with another character, Polemarchus: “Justice is doing good to friends and harm to enemies” (332d, p. 8).
While Plato doesn’t endorse either of these views, none of the characters in his Republic propose anything quite like the Golden Rule as a guide to living. Even Plato’s hero, Socrates, comes to a rather modest conclusion: justice is “minding one’s own business” (433b, p. 111).
The Golden Rule may not be a perfect guide to every situation—after all, people’s preferences vary. That would be one reason that holy books contain commentary, not just a simple statement of one rule for living. But the rule provides a good starting point: taking the perspective of other people rather than just looking out for your own interests.
The chimpanzees that I study in Tanzania act as if they live according to those two views from Plato’s characters: “might makes right,” and “do good to friends and harm to enemies.” Chimpanzees live in a zero-sum world of intergroup relations. A win for my group is a loss for yours. Most of the stories in history books—invasions, conquests, the rise and fall of empires—follow similar zero-sum rules.
This week marks the one-year anniversary of the Russian invasion of Ukraine. Since 24 February 2022, nearly every day has brought appalling new stories. Cruise missiles blasting civilian apartment buildings, schools, and hospitals. Massacres, torture, rape. The war seems anachronistic, a throwback to the tank battles of World War II and the trench warfare of World War I. In 1945, hoping to prevent World War III, the founders of the United Nations agreed to “live together in peace with one another as good neighbours,” vowing “that armed force shall not be used, save in the common interest.” The United Nations Charter signaled a profound shift away from the view that war is a legitimate tool of national interest, to something more like the Golden Rule.
Unlike chimpanzees, we don’t have to fight our neighbors. Instead, we can engage in mutually beneficial exchanges. We help each other out. We can trade information. Where is that migrating herd of wildebeest heading? Where is a waterhole that is not dried up? We can exchange favors. You can come hunt on my land for a while, if you let me take water from your land. We can exchange goods, such as decorative pigments and shells, and material for making tools. The archaeological record in Africa indicates the people have engaged in such trade for hundreds of thousands of years, based on the finding of materials such as obsidian many kilometers their sources—much further than people are likely have traveled on their own.
As humans, we depend on help from others. In recent centuries, developments in economics and technology have multiplied exponentially the ways in which we depend on others around the globe. A major lesson from the modern world is that everyone gains from living as good neighbors, and everyone loses from war. My hope is that Russia’s invasion of Ukraine will remind the world of the horrible costs of war, resulting in renewed efforts to build an international community based more on the Golden Rule than the law of tooth and claw.
Of course, while we can aim for an international community composed entirely of good neighbors, the world we live in contains bad neighbors, who must be dealt with. In the book of Luke, immediately before pronouncing the Golden Rule, Jesus proclaims:
“Love your enemies, do good to those who hate you, bless those who curse you, pray for those who mistreat you. If someone slaps you on one cheek, turn to them the other also. If someone takes your coat, do not withhold your shirt from them. Give to everyone who asks you, and if anyone takes what belongs to you, do not demand it back.”
Perhaps George Price, who underwent a profound conversion to Christianity late in life, had this passage in mind when working on the Hawk-Dove game, which he published in a 1973 paper with John Maynard Smith. In this foundational work of evolutionary game theory, the authors modeled “turning the other cheek” with the strategy of Dove: when conflict arises, retreat from the aggressor. In a world composed entirely of Doves, everyone would benefit: nobody would fight, so nobody would suffer injuries. However, mathematical and computer modeling found that the world of Doves is vulnerable to invasion by Hawks: individuals that always fight to take what they want. Everyone is worse off in a world with Hawks, but Doves alone cannot prevent a Hawk invasion. Doves can, however, invade a world composed of entirely of Hawks, because Doves avoid the costs of constant fighting. Maynard Smith and Price concluded that the Evolutionarily Stable Strategy consists of a mix of Hawks and Doves—or of individuals using a mixture of both strategies.
In the long peace that followed World War Two, the peoples of Western Europe learned to live as Doves, enjoying the benefits of being good neighbors to one another, rather than seeking conquest and empire. The mostly peaceful collapse of the Soviet Union in 1991 brought with it the hope that Russia too would become a Dove, and everyone would win. With the invasion of Ukraine, however, Russia revealed itself to be a Hawk. So long as Hawks exist, the Golden Rule alone will be an insufficient guide to international relations. To defend against Hawks, nations must instead follow the advice of Polemarchus: “Do good to friends and harm to enemies.” And if the logic of the Hawk-Dove game is sound, that there will always be Hawks.
(If you are interested in exploring the dynamics of the Hawk-Dove game, see this NetLogo version of the game developed by Kristy Crouse here. )
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, singlong, 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.)
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.
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).
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.
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!
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 behaviour, 58(4), 825-830.
Mercado, E., Herman, L.M. & Pack, A.A. Song copying by humpback whales: themes and variations. Anim Cogn8, 93–102 (2005). https://doi.org/10.1007/s10071-004-0238-7
Mitani, J. C., Hasegawa, T., Gros‐Louis, J., Marler, P., & Byrne, R. (1992). Dialects in wild chimpanzees?. American Journal of Primatology, 27(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 Behaviour61(6): 1203-1216. https://doi.org/10.1006/anbe.2000.1706
Work on this paper began back in August, 2012, when Kristy emailed me, asking for advice about graduate studies. Kristy had recently earned her bachelor’s degree from the University of Minnesota, where she had taken pretty much all of the classes I had taught over the past two years. When we met, she said, “I have a background in Anthropology and Computer Science. Is there anything I can do with that?” I had some ideas. We began meeting together to discuss them, together with Clarence Lehman, an ecologist who also has a professional background in computer science.
At the time, I had started to compile data on lethal aggression in chimpanzees. Male chimpanzees defend group territories. There are some obvious benefits to having a larger territory. Perhaps the most obvious benefit is that, all else being equal, a larger territory should have more fruiting trees, shrubs, and vines, providing more food for chimpanzees to eat. Analysis of long-term data from Gombe had found that when the territory size was larger, chimpanzees traveled in larger parties, and females reproduced more quickly (Williams et al., 2004). Controlling for age and reproductive state, individuals weighed more when the territory was larger (Pusey et al., 2005).
Another benefit of large territory size occurred to me. Chimpanzees are most likely to meet their neighbors along the periphery of their range. Geometrically, as the territory increases in size, the perimeter increases linearly, while the area of the territory increases by the square of the radius. As a result, with increasing territory size, the periphery should constitute an increasingly smaller proportion of the total range. If intergroup killings occur mainly in the periphery, and the periphery constitutes a smaller proportion of larger territories, then larger territories should provide an additional benefit: more safe area within the territory. As a result, overall risk of death from intergroup aggression should be smaller in larger territories.
Another consequence of this occurred to me. If mortality from intergroup aggression is lower in larger territories, then females should have higher fertility. Chimpanzees tend to kill male rivals more often than females, but they do sometimes kill females from other communities. More importantly, attackers often kill the infants of females from neighboring communities. In a larger territory, females should suffer fewer such losses, and so be able to produce more offspring. About half of these will be males, who stay in their birth community and add to the ranks of territorial males. With increased production of male defenders, chimpanzees in larger territories should be increasingly able to win intergroup battles, and thus further increase their territory size. A virtuous cycle would therefore ensue: larger territories reduce intergroup mortality, leading to higher female fertility, leading to faster production of male defenders, leading to greater odds of winning intergroup fights, resulting in larger territories. The rich would just keep getting richer, until some other factor, such as infighting within the group, led to a change, such as a group fission.
The geometry seemed simple enough. But would it hold up in reality? Real territories are not perfect circles. Intergroup killings could take place anywhere, not just along the periphery. We could test the model empirically with data, but good long-term data on such systems are scarce, and sample sizes are bound to be small. This seemed an excellent system to test using agent-based computer models.
Kristy set to work on the project, and soon developed a working model. She created artificial chimpanzees that lived in color-coded territories. They roamed their virtual landscape, and beat up on any neighbors they encountered.
And sure enough, analysis of the resulting data indicated that per capita intergroup mortality was higher in smaller territories.
In February, 2013, I presented on this model to the Behavior Group in the Department of Ecology, Evolution and Behavior in Minnesota. In addition to describing results from Kristy’s modeling, I also analyzed data from multiple chimpanzee study sites, collated for another paper (Wilson et al., 2014). Both the empirical data and the modeling data were consistent: individuals in larger territories experienced a lower risk of intergroup mortality.
This seemed to have implications for human societies as well. In a world of hostile neighbors, killing is most likely to occur along the edges of territories, where invaders first encounter defenders. Over historical time, the maximum size of territories has increased, from the home ranges of hunter-gatherers, to the city-states of early agricultural societies in places like Mesopotamia, to the empires that gradually grew and swallowed up those city-states. Are people living within empires safer than people living in smaller states, or in hunter-gatherer societies? Does the virtuous cycle of reduced mortality and increased fertility support the growth of empires?
Kristy applied to graduate school, and I began serving as her co-advisor, along with Clarence. In 2014, while I was on sabbatical at the University of Montpellier in the south of France, Clarence visited with me. We talked about this project we had been working on with Kristy. It seemed like with just a bit more work, we could wrap the paper up and submit it for publication.
Once Kristy started grad school, though, coursework and teaching and grant proposal writing and other pressing matters demanded her time. Moreover, Kristy wasn’t satisfied with her model. She saw ways she could do things more elegantly, so she continued to tinker with it. Work continued on the paper, and graduate student Nisarg Desai joined to help with statistical analysis. Finally, in the fall of 2019, Kristy submitted the manuscript to a high-profile journal. The editor rejected it almost immediately, without sending it out for review. This was discouraging. Kristy set the paper aside for a while to focus on her dissertation research.
We eventually developed the paper in two new ways.
First, we recruited additional collaborators to provide more empirical data. Kira Cassidy had published some very nice work on intergroup aggression in wolves, which parallel chimpanzees in many ways: they defend group territories, and have high rates of intergroup killing (Cassidy et al., 2015). I knew Kira from having served on her master’s thesis committee. I contacted her and asked if she would be interested in collaborating on this comparison with chimpanzees and virtual agents. She agreed, and brought in Erin Stahler, another biologist working on the Yellowstone wolf project.
Second, Kristy was becoming increasingly interested in a fundamental problem of agent-based models. How do you know that the model is doing what it is supposed to do? Every model is a simplified view of something more complex; an abstraction from reality, an approximate match to the real system. As British statistician George Box famously said, “All models are wrong, but some models are useful.” How do you know whether a model you have created is useful?
Other researchers in agent-based modeling and suggested methods for developing models to ensure the they match the target system sufficiently well to provide useful information about that system. How exactly to follow those suggestions, however, was not always clear from the existing literature. So Kristy took our paper as an opportunity to explore these issues in more detail. We had a simple geometrical model, an agent-based model, and two sets of empirical results from different species. These different sets of information provide ways to check one another, to give us more confidence that what we are modeling applies to real-world systems.
We submitted this revamped version of the paper to Ecological Modelling, where it has now been published.
We hope this paper will be useful to others, both for those interested in further exploring the impacts of territory size on mortality and those seeking to develop agent-based models of other systems.
Box, G. E. (1976). Science and statistics. Journal of the American Statistical Association, 71(356), 791-799.
Cassidy, K. A., MacNulty, D. R., Stahler, D. R., Smith, D. W., & Mech, L. D. (2015). Group composition effects on aggressive interpack interactions of gray wolves in Yellowstone National Park. Behavioral Ecology, 26(5), 1352-1360.
Crouse, K. N., Desai, N. P., Cassidy, K. A., Stahler, E. E., Lehman, C. L., & Wilson, M. L. (2022). Larger territories reduce mortality risk for chimpanzees, wolves, and agents: Multiple lines of evidence in a model validation framework. Ecological Modelling, 471, 110063. https://doi.org/10.1016/j.ecolmodel.2022.110063
Pusey, A. E., Oehlert, G. W., Williams, J. M., & Goodall, J. (2005). Influence of ecological and social factors on body mass of wild chimpanzees. International Journal of Primatology, 26(1), 3-31.
Williams, J. M., Oehlert, G. W., Carlis, J. V., & Pusey, A. E. (2004). Why do male chimpanzees defend a group range?. Animal behaviour, 68(3), 523-532.
Wilson, M. L., Boesch, C., Fruth, B., Furuichi, T., Gilby, I. C., Hashimoto, C., … & Wrangham, R. W. (2014). Lethal aggression in Pan is better explained by adaptive strategies than human impacts. Nature, 513(7518), 414-417.
In a recent opinion piece for Scientific American, John Horgan writes “Ending war won’t be easy, but it should be a moral imperative, as much so as ending slavery and the subjugation of women. The first step toward ending war is believing it is possible.” As part of his argument he declared that “far from having deep evolutionary roots, [war] is a relatively recent cultural invention.” We cherish the goal of ending war, but regard the claim of war being independent of our evolutionary past as unjustified, irresponsible and improbable. It is possibly based on a misunderstanding of what it means for a behavior to have evolutionary roots, but regardless of its derivation, we see it as dangerous. The problem is that if Horgan’s view prevails, we close our minds to potentially important contributions towards understanding the causes of wars.
Like any other sane individual aware of the power of nuclear weapons, we of course agree that is desirable to reduce major wars to zero. We consider this goal to be part of the “possibilist agenda” — an approach that begins by ruling out what is impossible, given the laws of the universe, rather than pessimistically focusing on what results are most probable to occur.1 Is ending war possible? Well, we don’t know of any laws of physics, or even principles of evolutionary biology, that would make it impossible to end war. The task before us remains finding the best means to achieve this goal. This includes gaining a clear, scientific understanding of what war is, what its causes are, and what factors can prevent it.
There are reasons for optimism. The examples Horgan cites shows that extended peace is a reasonable possibility, given that wars have been absent for decades in parts of the world. As Stephen Pinker described in exhaustive detail in his 2011 book, The Better Angels of Our Nature, deaths from international warfare declined steeply after 1945. Many of the richer countries that formerly engaged in long and bitter wars with one another — the United States, Japan, Germany, France, England — are currently closely allied in long-term friendships. The United States and Canada, for example, haven’t fought each other in earnest since the War of 1812, and as each other’s largest trading partners, benefit greatly from trading rather than invading. At the same time, the rise of authoritarian and nationalistic leaders worldwide, and events such as Russia’s invasion of Ukraine, provide reasons for concern.
We also agree that much about war involves “relatively recent cultural inventions.” Certainly contemporary weapons are entirely different from those used by the hunter-gatherers of Nataruk, Kenya, 10,000 years ago to execute their enemies, or by the several hunter-gatherer societies of India’s remote Andaman Islands who lived in permanent war with each other. Equally novel are the hierarchies that give leaders power to order warriors into battle, and the military training that promotes efficient tactics, and ideologies that encourage self-sacrifice even to the point of suicide, and the assembly of huge armies. There are many such novelties. But so what? They cast no direct light on the question of the antiquity of war, or more importantly on the question of whether the possible practice of lethal intergroup aggression by our remote ancestors has left a legacy in the human psyche.
Whether war has deep evolutionary roots remains an unsettled topic, contrary to Horgan’s assertions. For example, Horgan links to his 2016 blog post, in which he describes a study led by Hisashi Nakao of skeletal trauma in hunter-gatherers living in Japan 12,000 to 2,800 years ago, which reports that only a small proportion of skeletons showed evidence of violent death. However, as noted in a 2020 review by Mark Hudson and colleagues, “[i]ndividual finds of arrowheads embedded in human bones and other similar, clear-cut traces of violence have long been known in Japan as elsewhere.” Although Nakao and colleagues consider their findings to represent a low rate of violence, their sample includes cases of “blunt force injuries to the cranium and embedded stone and bone projectile points in the post-crania with no signs of healing – providing a prevalence of 1.8 per cent of adults dying violently.”
Do these data indicate a high or low rate of death from violence? The actual rate of deaths from violence is difficult to determine from archaeological evidence alone: not all deadly violence damages bones, and only a fraction of deaths end up in the archeological record. But if we take the rate of 1.8% adult deaths from violence at face value, this is about 2.5 times the rate of death from homicide in the United States in 20202, a year marked by a dramatic increase in violence. What does this tell us about the evolutionary roots of war? It provides additional evidence that people in prehistory faced a threat of death from violence, but also provides additional evidence that rates of violence vary across space and time, for reasons that are worth exploring further.
For anyone seriously interested in understanding the causes of war many other kinds of evidence are thought-provoking. Warfare is documented among hunter-gatherers in every inhabited continent, and was especially prominent where the neighbors were also hunter-gatherers rather than dominant farmers. Chimpanzees, our evolutionary cousins, practice a form of intergroup aggression that is strikingly similar to the hit-and-run aggression characteristic of human small-scale societies. In chimpanzees and in humans the initiators and the victims of lethal intergroup aggression are overwhelmingly males. In both species, males are more aggressive than females, a difference that starts long before maturity.
Why are chimpanzees and humans two of the few species of mammals that regularly take advantage of opportunities to kill members of neighboring groups? Are the reasons wholly different in the two species, or do they share some aspects of motivation and explanation, in which case, what are they? To rule out such questions is unworthy of an essay in a scientific journal. They concern topics being actively explored in behavioral ecology, evolutionary psychology and the neurosciences, among other areas.
There is much to learn, but we believe that some current hypotheses are helpful. One is that warfare has evolved from the human ability for proactive aggression. Proactive aggression involves making plans to attack vulnerable victims using overwhelming power, a practice followed by chimpanzees and humans. It benefits the aggressors by leading to increased territory size, or greater safety. Importantly, however, proactive aggression is very predictably inhibited when potential victims turn out to be sufficiently well defended that the aggressors risk getting hurt. Thus, even though proactive aggression is reined in for most of the time, it pays dividends under some circumstances; and human brains are likely very sensitive to such assessments. Would Russia have dared to invade Ukraine in 2014, much less escalated its attack in 2022, if NATO had accepted Ukraine’s application to join in 2008?
The challenge of preventing major wars is mainly undertaken by politicians and lawyers, but we think that every contribution might help. If a deep legacy of using coalitionary proactive aggression has left its mark on the human psyche, what does that mean for differences in war motivation between men and women? Or for how war leaders perceive the costs of wars in which they are directors rather than participants? Or for the point at which leaders will perceive the benefits of peace as outweighing the costs of war? Or for how individuals categorize others as friend or foe? Is it possible that the psychological mechanisms for evolutionarily-based risk assessments are predictably affected by certain medicines that could make leaders more or less risk-prone? If so, we should all be especially alert to a leader’s ailments. To ignore such questions is to bury one’s head in the sand.
Retaining an open mind about the etiology of war is surely the wisest course in a world still threatened by major conflict, despite the many institutional efforts, from the UN down, to control it.
Additionally, whether war has deep roots in our psyches, or is a recent invention like agriculture and empires, evolutionary game theory suggests that in looking to the future, we need to consider, not just our hopes and dreams, but also the strategies available to all players in the game. Players don’t act in a vacuum: they act in a world of competing strategists. We may prefer to plan for peace rather than war, but if other players pursue war as a strategy, we must either prepare to oppose them, or be defeated by them.
Russia might one day fulfill its promise of becoming a Canada to Europe and Asia: a peaceful, prosperous neighbor to the north. In the meantime, however, Russia’s leaders remain trapped in a zero-sum view of the world, seeing neighboring states more as opportunities for conquest than commerce.
As an example of a fatalism that will lead to more war, Horgan offers this quotation from Kaja Kallas, the prime minister of Estonia: “Sometimes the best way to achieve peace is to be willing to use military strength.” People living in Estonia, however, have bitter historical experience with being invaded and occupied. If you live next door to Putin’s Russia, rather than Trudeau’s Canada, the best way to prepare for peace may indeed be to prepare for war. International peace will not be achieved by simply giving in. Peace among nations surely requires making the costs of war so high that when appeals to law or morality fail, potential aggressors recognize that it is in their own best interests to find a constructive solution.
Horgan, J. (2016, April 4). Japanese study deals another blow to deep-roots theory of war. Scientific American Blog Network. Retrieved May 12, 2022, from https://blogs.scientificamerican.com/cross-check/japanese-study-deals-another-blow-to-deep-roots-theory-of-war/
Horgan, J. (2022, April 27). Will war ever end? Scientific American. Retrieved May 12, 2022, from https://www.scientificamerican.com/article/will-war-ever-end/
Hudson, M., Schulting, R., & Gilaizeau, L. (2020). The Origins of Violence and Warfare in the Japanese Islands. In G. Fagan, L. Fibiger, M. Hudson, & M. Trundle (Eds.), The Cambridge World History of Violence (The Cambridge World History of Violence, pp. 160-178). Cambridge: Cambridge University Press. doi:10.1017/9781316341247.009
Nakao, H., Tamura, K., Arimatsu, Y., Nakagawa, T., Matsumoto, N., & Matsugi, T. (2016). Violence in the prehistoric period of Japan: The spatio-temporal pattern of skeletal evidence for violence in the Jomon period. Biology Letters (2005),12(3), 20160028.
“Following the possibilist agenda means working tirelessly to imagine both possibilities and impossibilities and then laying plans to arrange events so that the desirable can be realized and the undesirable avoided—working to avoid unintended consequences. In this way, by superposing such thoughts onto recognized physical–biological–social problems of the world . . . seemingly intractable problems may have possibilist solutions.” PNAS [↩]
The conceptual lenses of evolution completely transform how we see the world.
For example, without thinking about things from an evolutionary perspective, a walk through my neighborhood on a morning in May is pleasant enough, but not particularly dramatic. Elm trees, oaks and maples stand along the boulevard, limbs stretched overhead to make the street a green tunnel, the blue sky barely visible beyond the canopy of leaves.
Honeybees and butterflies visit the irises blooming in the garden. A little black-capped chickadee perches for a moment on a branch above the birdhouse and opens his beak to sing his song, joining the chorus of that fills the morning air.
Looking at this peaceful scene through the lenses of evolution, though, reveals that this tiny little chickadee is a dinosaur. We know now that the dinosaurs didn’t disappear; in fact the number of living dinosaur species (10,000 or so) greatly exceeds the number of mammals (not quite 6,000). This chickadee, like all other birds, is a theropod dinosaur, distant kin to Tyrannosaurus rex. The more we learn about dinosaurs, the more we learn how much like birds they were. While it’s hard to be certain about the soft tissue, physiology and behavior of long extinct animals, various lines of evidence suggest that, like this chickadee, Tyrannosaurs was a feathered biped with a four-chambered heart, possibly with warm blood in its veins, and (perhaps) a devoted parent.
The song the chickadee is singing is no idle amusement to pass away the time. It is a matter of utmost importance to him. He sings to claim this territory as his own, to keep all rival males at bay. And why does he care so much this territory? Because this bit of yard and trees will be the home for him and his wife, the mate he seeks to woo with his song. The morning air resounds with the love songs of dinosaurs.
The flowers blooming in the garden and on the lawn are lovely in their own right. But viewing them through the lenses of evolution, we see that, like the songs of birds, they are all about sex. Each flower is a cunningly designed sex organ. The irises growing in the garden have large intricate blooms, with deep purple or yellow petals shading the male and female sex parts within: the female pistil, and the stalks of male stamens. Like the songs of birds, flowers are designed to attract mates. But flowers don’t have eyes, and they can’t move, so in order to mate, they lure other species to help them. While we humans find the vividly colored petals attractive, the iris is really aiming its message at the eyes of bees.
The bottom petal of the iris is an exquisitely designed landing platform for bees. A pattern of colors – likely including colors that bees but not humans can see, in the ultraviolet spectrum – guides the bees down a tunnel into the heart of the flower. There the iris provides the bee with a meal of nectar, while coating the bee with pollen as she sips her meal in the snug chamber. Each grain of pollen protects a cell that will give rise to two sperm cells. Dusted with flower sperm, the bee exists the chamber and flies off to another flower, playing its role in an interspecies ménage-a-trois.
The elms, oaks and maples whose boughs shade the street in green light seem peaceful enough. But viewed through the lenses of evolution, we can see that these trees are fighting a long, slow battle. Each tree is growing as fast as it can to reach the sun. Each tree has many enemies: the caterpillars that eat the leaves; the Dutch elm disease that gnaws at their roots; the summer storms that break their limbs. But no enemy is a more bitter rival than its neighboring trees. Each tree is fighting a slow struggle to reach the sun first, to spread their limbs wide and cover their enemy trees in the darkness of their shade. And why do these trees care so much for the sun?
The sun is life, their source of energy. Each tree is a solar powered sugar factory, holding thousands of flexible green solar panels up to the sky. Shade is death. The tree must grow high above the neighboring trees to reach the sun.
And why must the trees make sugar? So they can make babies. These trees have spent the spring having sex and making babies. Unlike irises and dandelions, though, these trees don’t rely on other species to have sex for them. Instead, they have sex with the wind, releasing their pollen into the air. Not long ago, the greenish yellow dust of tree sperm covered every surface outside: the sidewalks, parked cars, porches, and grills. Now the world is covered with the resulting babies: tree embryos in tiny packages. Some of them have wings: the helicoptering seeds of maples, or the tiny flying discs of elms. Floating in the breeze, and choking the grill of the air conditioner, are the tiny fluffy seeds of cottonwood trees. These trees, growing to giant size along the Mississippi floodplain, make the tiniest seeds, each suspended by a parachute of fluff.
Year after year, each of these trees makes thousands or millions of seeds. And almost every single one of these seeds will die before it becomes a tree, eaten by birds or squirrels, washed down the gutter to the storm sewer, dissected by children curious about what’s inside a maple helicopter. A fortunate few will land on soil where they can take purchase and sprout – only to be plucked by weeding gardeners, or eaten by rabbits or deer. Only a tiny fraction of all this abundant mass of seeds will ever grow into trees big enough to make seeds of their own.
Viewing the world through the lenses of evolution help us see that what seems to be a quiet city street is actually an unfolding drama of sex and violence: seductive flowers, battling trees, and dinosaur love songs.
In the Odyssey, the goddess Athena appears to young Telemachos in the form of an old man, Mentor. In this guise, Athena tells Telemachus what he needs to do.
At the University of Chicago, Amy Kass appeared to many of us as a Mentor. But she didn’t tell us what to do. She didn’t give us the answers. Instead, she asked us questions:
“Who is someone you think of as an example of human excellence?”
“Is it better to be a virtuoso, or virtuous?”
“What will be the most important decision that you make in your life?”
She didn’t dispense a particular body of knowledge to students: chemistry, physics, classics, literature, or philosophy. Instead, she served as a guide, helping students learn to read great books, and to think seriously about big questions in their lives.
I first met Amy Kass the summer after my junior year in high school, when I spent six weeks at the University of Chicago for a Telluride Association Summer Program. Amy and another great teacher, her husband Leon, led the seminar, Science and Society: Knowledge Morals and Power. Eager for more classes like this, I returned to Chicago for college, where I took Human and Being and Citizen with Mrs. Kass. We read Homer (the Iliad), Genesis, Aristotle (The Nicomachean Ethics), Shakespeare (King Lear), Rousseau (Discourse on the Origin of Inequality), Kant (Foundations of the Metaphysics of Morals), Dostoevsky (Crime and Punishment), Luke. We read about examples of human beings: Abraham, Achilleus, the Great Souled Man, Lear, Savage Man, Rational Man, Raskolnikov, Jesus. We talked about what, if anything, was excellent about these men (and looking back, yes, in that class, the exemplary human beings were all men).
Class took place in seminars: twenty or so students gathered around a set of tables arranged in a square. We read and we talked. Mrs. Kass asked questions. She was slender and small, with bright eyes and silvering hair. She leaned forward when she spoke, gesturing with her hand, looking intently at each student. We called each other by last names and titles: Mr., Miss, or Mrs. Everyone had a place at the table, and the value of your ideas didn’t depend on your title or rank. Everyone was treated as an adult, and with respect. She encouraged us to speak our minds, and to disagree with her and one another, but to do so through discussions (“What is right?”), not arguments (“Who is right?”).
Mrs. Kass didn’t lecture. She didn’t tell us her views on things, at least not directly. She asked questions and listened to our answers. She knew our names, she knew who we were, and despite her years of teaching these books to students, she seemed genuinely interested in what we had to say about them. How often does a class of first year college students say something really new or surprising about Homer or Shakespeare? But she never seemed jaded or condescending towards her students. She wasn’t interested in whether we could say something clever or novel; she was interested in our development as readers and thinkers.
She led us through the readings slowly. She asked a student to read a passage, then we discussed what it meant. We might spend an entire class period discussing a few such passages.
Mrs. Kass helped teach us to read.
I didn’t know how to read when I started college. Even by the time I finished college I’m not so sure if I could read; these lessons have taken time to really sink in. Oh, I read lots of books, but I skimmed along the surface, and often didn’t even understand the surface. Too often, reading was something I did at the end of a long day of lectures, labs and problem sets, slouching in a big chair in a bay window of the Regenstein Library, underlining and querying a few puzzling sentences before dozing off.
But in class, we read aloud, we read slowly, and we read for understanding.
Mrs. Kass began a discussion of Book IV of The Iliad by asking, “If I asked you who you were, what would you tell me?”
“I’m a 20th Century American.”
“And how does Homer introduce these men? Who is, say, Echepelos?”
“He’s… um….” searching the page for the name, “Thalysias’s son.”
Okay, there’s his name a few lines down. “Chalkodon’s son.”
In the world of The Iliad, you weren’t an isolated human being, or an undifferentiated member of a particular society in a particular time. You were someone’s son or daughter.
Then we moved on to the next page, where Antiphos, a son of Priam, killed Leukos, “a brave companion of Odysseus,” as Leukos was dragging off a corpse. Odysseus, “stirred to terrible anger,” struck down Demokoön, a son of Priam.
Mrs. Kass asked, “Why did Odysseys kill Demokoön, and not Antiphos?”
I hadn’t even thought to wonder about this; my eyes had glazed over in the series of seemingly random, bloody killings on the battlefield.
Mrs. Kass persisted. “Who is Demokoön?”
“He’s Priam’s son. Oh. Odysseus killed his brother.”
Instead of seeking revenge by killing the killer, Odysseus inflicted a more painful, longer lasting wound, by killing the killer’s brother. And so a seemingly unimportant detail was revealed as an illustration of the cruel wisdom of Odysseus.
With Mrs. Kass, we read old books. The most recently written thing we read was Dostoevsky’s 1866 novel; not one of her favorites, and one that must have been chosen by others on the course committee, judging by a comment she made after a class spent discussing this book: “This is my punishment; what was my crime?”
One thing we learn from the standard university curriculum is how wrong people were in the past. Aristotle appears in science textbooks mainly as someone who got things wrong: that a heavier object falls faster than a lighter object; that there are four basic elements; that the sex of human babies is determined by temperature. We learn about Descartes’ error (mind-body dualism) rather than anything he got right. The basic lesson of the textbooks is: people in the past were ignorant. They didn’t know germ theory, or atomic theory, or evolution.
And it’s not just in the remote past that people were ignorant. By the time I reached college, scientific views of the solar system, of dinosaurs, and so many other things had changed dramatically from what I remembered learning as a child. Every year, we know so much more than we did before.
It’s easy – and self-gratifying – to be smug about how smart we are today. We know so much more. We are right about so many things.
Mrs. Kass helped us see that despite how much we know now, we still had much to learn from close reading of Homer, Aristotle and Shakespeare, even if they are Dead White Males, even if they lived before the discovery of quantum physics and the genetic code, even if their views on politics and religion might sometimes seem old fashioned (though perhaps not always so old fashioned as one might expect). She helped us understand the difference between knowledge and wisdom.
Despite all the changes over centuries and millennia, much about the human condition remains the same. We are born, we grow up, we search for a path to follow. We seek love and friendship. We may marry, we may have children. If we live long enough, we grow old. Whether we live long enough or not, we die. Even people admired for excellence have their quirks, weaknesses, and sometimes terrible, fatal flaws.
Universities have plenty of classes that provide answers. But few classes ask questions. And hardly any classes ask questions that are really the most important ones for young people trying to find their way in life.
When Mrs. Kass asked her class, “What is the most important decision you will have to make,” most students answered something to do with their careers. One young man responded: “Who will be the mother of my children?”
The answer sounded old fashioned, and embarrassingly serious. But really, what could be more important?
I wanted answers. I wanted to know. While we were reading Kant, I asked Mrs. Kass what was her foundation for morality. She threw up her hands and laughed. “Standing on one leg?” she asked.
If it were that easy – if you could give an answer to this question, standing on one leg like a circus performer – then we wouldn’t need to spend hours reading, thinking, and discussing these questions. A short lecture on moral foundations would do.
We read about many different kinds of human excellence, but none of these literary examples struck me as vividly as the example of Mrs. Kass herself: intensely smart but never merely clever or showy; respectful, but not afraid to question or disagree; inclusive; courageous; serious yet also wry, funny and good humored; challenging us all to be better.
The last time I saw Mrs. Kass, she was discussing with a young person an assignment for a class on Shakespeare, taught by someone else. The student had developed a particular view of how to interpret a passage, but was worried that her teacher would disagree with this interpretation. Mrs. Kass asked her, “Do you want a good grade? Or do you want to be right?”
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.
Dyson, G. (2012). Turing’s Cathedral: The Origins of the Digital Universe, Pantheon.
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.
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.
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.
A, B, C, D, E, F, G…
A, C, G, T
Dog, cat, in-, un-,-ness
CAT, TAG, DAT, DCG
Dog, cat, catness, undoglike
hemoglobin, melanin, lactase, amylase
My particular speech
My particular genes
Upper Midwest American English
Homo sapiens sapiens
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).
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.
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.
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.
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.
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.
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:
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.
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.
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.
There they find a single blue male off by himself.
Bad luck for the blue male! The red males surround him, gang up on him, and kill him.
Now Blue only has 9 males.
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.
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.
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:)
Hearing a single stranger calling in the distance had a big effect on the chimpanzees.
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.
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.
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.
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:
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.
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?
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.
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.
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.