A third step in this sort of program of research is to take these problems to a more neuro-physiological level. In collaboration with neuro-scientists throughout the United States and internationally, we've begun some experiments to look at how the brains of rhesus monkeys in particular decode information about their vocalizations. Using recordings from neurons in the various auditory areas of the brain we play back vocalizations from their repertoire and see how their nervous system actually decodes that information. This is relatively new work; for a long time now we've gained an incredible amount of knowledge about the neurobiology of vision from using rhesus monkeys as a model. Almost nothing has been done in terms of auditory function. And yet when we think about language we really know nothing about the evolution of language and speech because we know very little about the neuro biology that underlies this fantastically complex system. Now, for the first time, we have the tools to acoustically probe how the non-human primate brains actually encode and decode these vocalizations. There is a long history of this kind of work with insects, birds, frogs, and bats, but almost nothing on our closest living relatives, the primates.

The fourth is comparative studies that I alluded to earlier where we do the same experiments with human infants that we can do now with non-human animals. This allows us to make direct comparisons of the abilities of humans and non-human animals with the same kind of task. As an example we explore the numerical abilities of human infants and non-human animals, using these kinds of techniques of magical violations to explore the kinds of representations they bring to the task of enumeration.

Thus, we have a 4-pronged approach to understanding the design of animal brains that goes from the field taking what ecological and social problems would have designed their brains the way they are, back into the lab to more systematically evaluate what we think are the representations underlying those problems in the wild, to the neuro-physiological level, which gets at a very mechanistic level of how a brain may generate mental states, and then finally comparing directly non-human animals with human infants so we can compare developmental processes with evolutionary processes.

JB: Do animals think and why do we care?

HAUSER: There's always this question about whether animals think and if so what are they thinking about. One of the things that's held back studies of animal cognition in terms of their integration with the cognitive sciences is that people have been obsessed with the question of intelligence, in the same way that we've been obsessed with human intelligence. That's often been a detour in our understanding of cognition. The same has been true for animal studies. People have been concerned with questions like are dogs smarter than cats; are dolphins smarter than pigeons; are chimpanzees smarter than dolphins; are we smarter than them; if so when did we become smarter than them? These are not good questions. The more interesting question is to evaluate what animals have to deal with in order to survive. Each species is intelligent in its own way. The question for me is not "Are animals intelligent, and do animals think?", but rather more specific questions we can answer, like "Can animals remember things? And if so how far back in time can they remember? Do they have memories of what they were like when they were young? Can animals learn about abstract properties of the world, and if so, why would they learn about them?" These are questions that we can ask, and I believe, answer with the tools of science. If you then want to say that, given those abilities, those are intelligent animals, that's fine. If you want to say that here are the ways in which animals communicate and that looks like language, that's fine with me too. It seems to me, however, that a more interesting question is to say, when humans communicate they have this interesting capacity to refer to things in their world. I can talk about a chair, I can talk about my past, I can talk about the future in a very abstract way. Do animals have that capacity? If they do then it looks like our system of communication. Those seem to me much more interesting problems, and tractable from an empirical perspective. We can say "Do animals have the moral emotions? Can they empathize? Do they feel guilt? Do they feel shame? Are they loyal? Do animals have the capacity to cooperate? Do they engage in reciprocal altruism? These are questions we can answer. They are difficult questions, but we can at least try to make some headway, and in many cases, we have made a great deal of progress. So I don't ask the question do they thin?; I don't ask the question are they intelligent?. I ask more specific questions that have to do with particular cognitive mechanisms that we know we can identify in humans, both infants and adults, and therefore we've got at least sensible questions to ask and therefore address. That's how I approach that question. I don't want to set up a taxonomy of intelligence among animals; I want to compare them in terms of their abilities. If somebody else wants to impose a taxonomy of intelligence that's fine.