A Natural History of Peace

THE NAKED APE

The evolutionary biologist Theodosius Dobzhansky once said, "All species are unique, but humans are uniquest." Humans have long taken pride in their specialness. But the study of other primates is rendering the concept of such human exceptionalism increasingly suspect.

Some of the retrenchment has been relatively palatable, such as with the workings of our bodies. Thus we now know that a baboon heart can be transplanted into a human body and work for a few weeks, and human blood types are coded in Rh factors named after the rhesus monkeys that possess similar blood variability.

More discomfiting is the continuum that has been demonstrated in the realm of cognition. We now know, for example, that other species invent tools and use them with dexterity and local cultural variation. Other primates display "semanticity" (the use of symbols to refer to objects and actions) in their communication in ways that would impress any linguist. And experiments have shown other primates to possess a "theory of mind," that is, the ability to recognize that different individuals can have different thoughts and knowledge.

Our purported uniqueness has been challenged most, however, with regard to our social life. Like the occasional human hermit, there are a few primates that are typically asocial (such as the orangutan). Apart from those, however, it turns out that one cannot understand a primate in isolation from its social group. Across the 150 or so species of primates, the larger the average social group, the larger the cortex relative to the rest of the brain. The fanciest part of the primate brain, in other words, seems to have been sculpted by evolution to enable us to gossip and groom, cooperate and cheat, and obsess about who is mating with whom. Humans, in short, are yet another primate with an intense and rich social life -- a fact that raises the question of whether primatology can teach us something about a rather important part of human sociality, war and peace.