Wild Minds: What Animals Really Think. - Brief Article - Review - book review

Wild Minds: What Animals Really Think, by Marc Hauser. Henry Holt; $25; 315 pp.

Specializations do not make one species "smarter" than another, but they do make for uniquely sculpted minds.

Do animals think? And if they do, how similar are their thoughts to our own? Traditionally, scientists have taken two approaches to cognition in animals, with the "liberals" (often those who study wild animals) arguing that there are clear parallels between animal and human thinking and the "skeptics" (often those who focus on captive animals) defending the uniqueness of the human mind. Harvard psychologist Marc Hauser is in an ideal position to evaluate the nuances of both positions, because in addition to observing and running experiments on cotton-top tamarins in the lab, he has studied vervet monkeys in the Kenyan savanna, chimpanzees in a Ugandan rainforest, rhesus monkeys on a Caribbean island, and crows on a California golf course. Plus he knows and lucidly cites the work of the evolutionary biologists, ethologists, neuroscientists, developmental psychologists, and cognitive scientists who have contributed to this burgeoning field.

Hauser introduces us to an extraordinary range of feats of cognition by animals from the New Caledonian crow, which constructs and modifies tools, to Clark's nutcracker, which uses its extraordinary spatial memory to locate during the winter the 30,000 or so pine nuts that it stored during the fall. In this thoughtful book, Hauser gives evidence to support both the skeptical and the liberal camp. Believing that language is unnecessary for certain kinds of animal cognition, and that we must look at the environments in which animals evolved to understand what they think and feel, he concludes, "We share the planet with thinking animals."

All animals, according to Hauser, have the mental tools for three distinct tasks: recognizing objects, evaluating quantity, and navigation. But how do we know that animals universally possess these capacities, and how do these abilities expand or contract in particular species? In experiments with tamarins and macaques, Hauser adapted a technique used by developmental psychologists to show that preverbal infants understand cause and effect, are able to discriminate quantity, and know that objects exist even when they can't be seen. Like infants, Hauser's monkeys show little interest when two toys are lowered behind a screen and the same two toys are revealed when the screen is raised. But both monkeys and infants demonstrate that they know when the number has changed: if there is only one toy or if there are two different toys when the screen is raised, both look longer at the scene.

Other cognitive abilities appear to be restricted to a few species. Great apes that encounter mirrors demonstrate self-awareness. If a researcher surreptitiously places a mark on a part of the ape's face that it can see only by using the mirror, some of these animals react by immediately grooming the spot, suggesting that they recognize images of themselves. To date, however, no monkeys have unequivocally passed this test, so perhaps self-recognition and self-awareness are mental properties limited to humans and apes.

Self-awareness is closely related to another ability: awareness of what others know and don't know. Teaching requires this skill, as does successful, deliberate deception. Some studies of great apes and monkeys suggest that these primates both teach and deliberately deceive, but few such findings exist for other species.

Humans, according to Hauser, are unique in having a language system capable of expressing abstractions and of producing and understanding unpredictable combinations of words. Although some monkeys make vocalizations that refer to specific objects (East African vervets distinguish between eagles and snakes) and other species (chickadees and titi monkeys) have simple grammars, nonhuman animals (including our closest relatives, the great apes) cannot create novel utterances, although some dolphins and apes understand novel sentences.

Morality also appears to be absent in nonhuman animals, according to Hauser, despite a wealth of anecdotes to the contrary. Emotions of guilt and shame have not yet been clearly demonstrated by systematic observations and controlled experiments. Even though acts of reciprocal altruism, cooperation, reconciliation, and empathy have been documented in animals (especially apes), Hauser questions whether such behavior should be categorized as moral, because we don't know if the animals are thinking about these actions the way we would. I was surprised at his requirement of uniformity in this case, since on other levels of behavior he accepts the notion that birds and monkeys may code information about objects, quantity, and space differently than humans do. "Although there is some evidence that animals have self-recognition," writes Hauser, "there is no evidence that they are actually aware of their own beliefs and desires.... Without self-awareness, the kind of empathic response that appears to underlie some of the experimental results described is impossible."

Wild Minds provides a clear and critical survey of mental capacities in animals and introduces us to new experimental methods--especially in developmental psychology-for studying these processes in animals. Unfortunately, the book says little about the evolutionary pressures that led to human cognition. What selective advantage is gained by our having a complex and open language system? Why have we evolved self-awareness? Why was it adaptive for humans to develop a moral sense? We need to understand what led to our own mental abilities in order to analyze why it hasn't been equally beneficial for apes, monkeys, birds, or rats to have similar abilities.

I wish Hauser had spent more time comparing the mechanisms of cognition in humans and animals. Until recently, most of our understanding of human brain function had been dependent on abnormal samples of brain activity in victims of closed-head injury or stroke. Because of advances in brain imaging techniques, however, neuroscientists can now examine normal human cognitive and emotional activity. Such imaging is certain to give new insights into the workings of animal minds as well.

Charles T. Snowdon, a psychologist at the University of Wisconsin, studies primate communication and edits the Journal of Comparative Psychology.