EDGE 3rd Culture: Marc Hauser: Animal Minds
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A Talk With Marc D. Hauser

MARC HAUSER: The big questions that are on my mind are of puzzles that we have no answers for. Those questions are things like, why are humans the only species that cries with tears? It's true that the emotions supporting crying with tears are common with humans and animals, and yet we're the only species that ends up generating a physical output of the emotion. If you look at crying with tears from an evolutionary perspective, which people really have not done, you begin to get some of the answers. Unlike all of the other emotional expressions, tearing as an emotional expression is the only one that leaves a long-term physical trace; it blurs one's vision, therefore it's costly; it's very difficult to fake; and what this then converges on is an idea that the evolutionary biologist Zahavi proposed many years ago which is that signals that are costly to produce are often honest signals, because those that do not have the resources to produce them would be unable to generate them. You can look at a signal and infer its honesty based on the cost of expression. Crying with tears is potentially one of those — even for actors, it's necessary for them to have the feeling before they can generate the expression, and even then it's quite hard to do it naturally.

We know that animals have things like sadness; whether they have joy is hard to say, but they certainly have the emotions that would accompany crying with tears even if they don't have that connection. It's not that they don't tear from the eyes, because they do if the eye is physically irritated; it's that somehow in the brain there's a connection missing. To say that they lack the connection in the brain is an answer at only one level of the analysis, which is the mechanism — what brain mechanisms support tearing. The more interesting question is to take the evolutionary approach and ask why we cry with tears and other animals do not? And the answer comes from thinking that it's an expression which really conveys honesty.

For the past few years I have been using the theoretical tools from evolutionary biology to ask questions about the design of animal minds. I'm particularly interested in taking the approach that some people have had within evolutionary psychology, and saying look, this whole notion of the environment for evolutionary adaptedness which people have pegged as being associated with the hunter-gatherer period in the Pleistocene, may be true for some aspects of the human mind, but are probably wrong as a date for many other aspects. If we think about how organisms navigate through space, recognize what is an object, enumerate objects in their environment — those are aspects that are probably shared across a wide variety of animals. Rather than saying that the human mind evolved and was shaped during the Pleistocene, it's more appropriate to ask what things happened in the Pleistocene that would have created a particular signature to the human mind that doesn't exist in other animals.