Baboons are not as lionized in the popular imagination as chimpanzees, primarily because baboons are not cute. (Nor are they endangered.) But they’re advanced primates, and by studying them we can learn a lot about how our own ancestors must have lived and behaved.
I’ve been reading a fascinating book called Baboon Metaphysics, by Dorothy Cheney and Robert Seyfarth. They have spent literally years studying a troop of baboons in the wild, in the baboons’ native habitat in Africa. The main purpose of this study has been to learn how baboons understand the world, and in particular how they see and relate to other baboons.
I’m not going to try to summarize the whole book here. The point that I’m pondering today is this: Unlike humans, baboons seem not to have a “theory of mind.” That is, their behavior seldom or never seems to take into account what other baboons may be seeing, thinking, or feeling.
Human social interactions, in contrast, are almost always based on our considerations of other people’s perceptions. Years ago, I read a comment — I don’t remember where — to the effect that all human conversation, every utterance we make in a social setting, is an attempt to influence the thinking, and thus the behavior, of others. But in order to even consider that influencing others would be useful, we need as a prerequisite to have a view of the world that incorporates the notion that others have thoughts and perceptions, and that their thoughts and perceptions may be quite different from our own.
You may think this view of social conversation is too extreme. (See, there I go — forming a theory about what you may think!) But as simple a question as, “How are you?” presupposes that the person you’re facing has an interior state that is not immediately observable. You’re asking for information about that state, and the reason you’re asking is because you feel a need to synchronize your thoughts and feelings with the other person’s in some manner.
How and why might this human ability have evolved? Clearly, it did evolve. At some point our remote ancestors, who were a lot like baboons, didn’t have it, and at a later point they did, so it must have conferred some selective advantage. I have no clear ideas about this; I’m going to have to think about it. Clearly, the ability is not necessary for survival in the wild in Africa, because the baboons are doing fine without it.
It seems to me that the ability to form a theory about another person’s mental state is closely linked to the use of language. Language is what gives us fine-grained access to others’ mental states, and also gives them access to ours. Language is not necessary for the basic perception of others’ states; you can judge a lot by facial expression and other cues. But in order to form a judgment, you need to have the idea that there’s something to judge, and language provides a much better means than simple observation for learning what’s going on in another person’s mind.
But did complex language evolve first and then a perception that others have interior mental states evolve as a result? Or was it the other way around — did language perhaps evolve as a tool with which to allow us to trade information about our mental states, when we had already developed the ability to know that those states existed?
I incline toward the latter view. I also suspect that the use of primitive stone tools is part of the equation. Many species, even parrots, can use tools opportunistically when the need arises and a tool is handy, and chimpanzees will make a tool out of raw materials if they need it, by stripping the twigs off of a stick, for instance. But while a young chimp may learn how to make a tool by watching her parent make one, it’s not likely that a chimp mother ever sets out to teach tool-making to a youngster.
That would require a theory of mind: It would require the perception, “I know something that my child doesn’t know.” Clearly, if you have such a perception and are moved to act on it, you’re increasing the likelihood that your child will survive long enough to have offspring. That’s one possible route by which a theory of mind might have evolved. Once you start knocking flakes off of rocks so as to form a sharp edge, teaching your children how to do it becomes an evolutionary highway that leads straight to cultivation of crops, gunpowder, the Internet, and lots of other cool stuff.