JB: What are you bringing to the table that's new?

HAUSER: The newness is both methodological and theoretical. The methodological is a little bit easier to identify. A large number of researchers working on animal cognition have had an almost myopic focus on making animals seem human. So we engage in all these exercises to show that through extensive training procedures we can make a pigeon look like a human. Now that is an interesting exercise, because it shows that at least at some level, the brain of an animal has the capacity to learn something, but what interests people working on humans, primarily about human thought, is what we do spontaneously in the absence of any training. It is clear that we can be trained to do extraordinary things. And that is an interesting aspect of the human mind. But what's more interesting, in part, is the spontaneous stuff because that's probably what's going to tell us most about the signature of evolution.

We are working with techniques that allow us to identify what animals spontaneously bring to the table in terms of how they think about the world. And that is a relatively new approach. It's not completely novel; people like Dorothy Cheney and Robert Seyfarth have been doing these kinds of experiments with animals in the wild, which clearly involved no training, and simply ask animals in their natural habitat what they are doing. We have taken advantage of those kinds of techniques and done similar experiments in captivity. The theoretical push that we have made is to unite evolutionary theory with modern ideas in cognitive science in a way which is very novel. One of the problems with evolutionary psychology is that it has had a very narrow focus on humans. Evolutionary psychology, broadly defined, has actually been going on since the days of Darwin. Darwin asked questions about the mind with an eye to evolutionary intuitions. What we're now seeing with the work that I've been doing is a real emergence of Darwin's initial intuition — that we can really marry, in a serious way, evolutionary theory with the cognitive sciences, as applied to the study of animal mind.

We ask questions about the design of the brain, the design of mental states by looking at how social behavior and ecology shape those processes. For example, we've recently been interested in the extent to which animals have a domain of knowledge that you might call naive physics. To what extent do animals make intuitive predictions about physical objects, based on the physics of the world. These kinds of questions would not have been asked if one were not sensitive to the kinds of statistical regularities that animals confront in their environment. It is true that all animals throughout our planet are confronted with the problem of gravity. When objects fall, they fall straight down — except of course if deviated by an object that gets in the way of the falling object. What we've been able to do is use the regularities that animals confront to ask questions about what kind of biases they bring to working their way through the world.

For example we have created an experimental procedure that follows along some of the work that's been done with human children, where you drop a ball through an opaque tube that has an S-like configuration. If you understand the way tubes work you should predict that the object will fall out at the end of the tube. Monkeys, and human children, expect the ball to land directly below the release point. They seem to be bringing gravity biases as a predictive force in their decisions. This is a problem, because it shows the great difficulty that children and some animals have inhibiting or suppressing a very strong bias that has been selected for because of the statistical regularities in the world. That is, gravity is a regularity that all animals on Earth confront. Consequently, rather than learn about the forces of gravity, I believe that selection favored brains that, innately, made predictions about falling objects. Because of this innate sense, it is difficult for animals to override their intuitions when the evidence goes against their beliefs.