Dear David Livingston Smith,

I must first of all commend you on your willingness to broach this controversial topic. In 1975, my book Sociobiology garnered much criticism from my colleagues, not because of its theories but because of the application of those theories to humans. I stated that our actions and behaviors originate in our genetics; given the thesis of your book, you agree. Many people assumed I was harkening back to the dark days of evolutionary biology as racist pseudoscience, and in fact protested against and threatened me. I think they vastly misunderstood my point, but you obviously did not. Denying the evidence that human behavior has been influenced by our genetic inheritance requires a level of self-deception I believe you would object to (Of Ants and Men).

You put forth the theory that humans have evolved to be aggressive, and our refusal to admit so makes it more difficult to escape the grasp of our violent inheritance. War, or more generally aggression, is not unnatural or inhuman; it is a regrettably large facet of human psyche that continuously influences our actions (Smith 1-8, 31-39). As I mention, I got quite a bit of flak for my idea that behavior evolves like other genetic traits. It’s gratifying to see other thinkers using the idea of sociobiology to explore different aspects of humanity.

Before I continue, I would like to explain a few of my theories, because the ideas in your book seem quite comparable. I coined the term eusociality to describe the highest level of social interaction observed within a species; ants are the most obvious example, as well as termites and wasps. Humans are the only primate species, out of the nineteen ancestral lines, who developed eusociality. I have defined eusocial species as having three traits: groups of individuals that live together for more than two generations, adults caring for their young, and a reproductive division of labor. Our care for children, ours and others’, is quite an obvious facet of our species, as is our propensity to live in multigenerational communities. Reproductive division of labor is less obvious in humans, but it is present; we usually call it altruism. Altruists are those who risk their lives for the benefit of others, giving up their chances of reproduction so that others can do so. Human eusociality has given rise to tribalism: the need for belonging and security that drives us to form communities and societies. Of course, when these communities are at odds, it results in brutal exclusion, which has a terrible capacity for cruelty and violence (Of Ants and Men).

In your first chapter, you state two aspects of early warfare. There are the ceremonial battles, where men fight with every intention of returning, and it ends when they wish to return home before dark. The other side is what you call “raiding parties,” a relatively small group of warriors who hunt down the vulnerable members of the enemy and kill or enslave them (Smith 13). As you mention, this is the first example of what we call war. Your definition of war is “premeditated, sanctioned violence carried out by one community (group, tribe, nation, etc.) against members of another” (16, 12-16). I believe this exemplifies the brutal exclusion in tribalism, wherein the loyalty humans have for their community creates a kind of collective ecstasy when they are in competition with another group (Of Ants and Men).

There are two discoveries in prehistory that you claim created war as we know it: the development of raiding parties and societal changes brought about by the agricultural revolution. Raiding was the hunting of other humans, which, as I said previously, is the first example of war as you have defined it. The settlement of societies and the advent of agriculture made communities easier targets for other humans, and increased competition between humans for resources. Early agricultural civilizations, by necessity, had to protect themselves from aforementioned raiding parties as well as ensuring each member of the community was provided for. This drove technological developments in weaponry and defensive architecture. Resource competition increased aggression between societies, elevating war to a new level of violence. The cruelty you describe might seem like damning evidence against instinctual altruism, but to me, this is brutal exclusion driving territorial expansion: the urge to protect the community encouraging the search for resources (Smith 43-52 and Of Ants and Men).

In order for a trait to become widespread in a species, it must be selected for, as you explain. In terms of natural selection, you state that aggression increases the likelihood of that individual gaining resources and surviving to pass on their genes. In terms of sexual selection, aggression eliminated other male competition and increased the individual’s perceived attractiveness. War give men the opportunity to gain higher social status, which likely meant they could conceive children with more women, or multiple women at once. It also unfortunately provided opportunities for rape, which, while reprehensible, did increase the individual male’s reproduction (Smith 62-70, 86-92). While you are correct that aggression is a trait that was useful and therefore selected for, I believe you overestimate its impact. Humans, as eusocial creatures, perform multilevel selection: selection on the individual level but also group selection, which prioritizes the community above the individual in terms of survival. You might think that altruistic people giving up the chance to reproduce means their altruism doesn’t pass the test of natural selection, but I personally think humans have proven to have a higher chance of survival through cooperation (Of Ants and Men).

You chose chimpanzees, baboons, and bonobos as examples of non-human warfare, or lack thereof, because of their extreme genetic similarity to us. Chimps fight viciously, with small groups of males patrolling the community’s boundaries and regularly invading others’ territory; when they encounter outsiders, they brutally kill them. As you mention, communities of chimps will attack other communities with the intention of wiping them out. In contrast, baboon fights consist of posturing and intimidation, where injuries are rare and casualties even more so. Bonobos rarely fight at all; they prefer to make love, not war. The chimps’ aggressive behavior, as you describe, has much in common with early humans’ raiding parties, which makes sense once you recall that chimps “share a whopping 98.77 percent of [our] genes.” (Smith 74, 71-80). I agree that chimpanzee behavior makes a compelling case for genetically influenced behavior, but I don’t believe it’s quite so close. Unlike chimpanzees or even bonobos, humans are a eusocial species. We cooperate more than other primates when faced with higher stakes. The psychologist Michael Tomasello performed an experiment wherein human toddlers were proven more likely to cooperate and share food than chimps (Of Ants and Men). Chimps’ and baboons’ sociality is limited to their own community, and they are not altruistic. For all their social behavior, bonobos express only individual selection, not group or multilevel.

Your book, it must be said, is quite the fascinating read. I thoroughly enjoy the pursuit of knowledge, especially in regards to our own species. The theory you put forward is well thought out and thoroughly researched, as well as logical and thought-provoking. While one might think I would disagree, given that my theories of human behavior are mainly about our altruism and eusociality, I believe you are entirely correct. One only has to look at our long history to see the large propensity for war; my own home state considers the American Civil War a vital part of our history, for good or ill. I think as our cooperation evolved, so too did our aggression. The unfortunate flip side of tribalism is brutal exclusion, which I believe is where your theory fits perfectly.

Sincerely, Ed Wilson

Works Cited