TCS Daily

Pondering Animals

By Kenneth Silber - May 19, 2004 12:00 AM

In the 1960s and 1970s, amid reports of sign-language-using chimpanzees and big-brained dolphins, an expansive picture of animal intelligence took hold in public opinion and among parts of the scientific community. The view that some nonhuman species possess considerable capacities for reasoning, language and self-awareness remains popular today, and has been a factor in the rise of the animal-rights movement.

There is, however, an ongoing scientific debate about the scope and nature of animal mental abilities, and much expert opinion has shifted in recent decades toward a more restrained and skeptical view. In Do Animals Think? (Princeton University Press), psychologist Clive D.L. Wynne presents an interesting disquisition imbued with such skepticism. The book is wide-ranging, including discussion of animals that have remarkable specialized capabilities (bats, pigeons, honeybees) as well as those (apes, dolphins) that are prime candidates to possess a broadly developed intelligence.

Wynne evokes the metaphor of a "similarity sandwich" to compare human and animal mental capacities. There is an underlying level of dissimilarity in sensory faculties; animals that detect ultraviolet or infrared light, for instance, perceive the world very differently. There is a layer of similarity; numerous species share basic psychological functions such as memory formation, recognition of objects, and sense of time. But the sandwich's top layer consists of cognitive abilities essentially unique to humans; these include language skills, and the ability to imagine the perspectives of other individuals.

Consider language. In the 1960s, a chimp named Washoe was taught to use over 130 words in American Sign Language. There followed other evidently language-using apes, including Nim Chimpsky (named after linguist Noam Chomsky). But in the late 1970s, psychologist Herbert Terrace roiled the field by concluding that his sign-language training of Nim had taught the chimp merely that certain hand and arm movements produce rewards. This brought growing attention to ape linguistic limitations, such as scant vocabularies and incomprehension of basic grammar.

Perhaps chimps have difficulty grasping human language, but have their own elaborate communication systems in the wild? Wynne points out research that indicates natural chimp communication is actually quite limited. The "pant-hoot" calls of wild chimps in Tanzania do not seem to be "referential," or referring to food sources or other things in the outside world. Meanwhile, animals such as vervet monkeys and even honeybees do engage in referential communication. Animal communication abilities seem to be not so much a predictor of intelligence as of the degree to which animals are socially cohesive.

Wynne describes experiments probing whether chimps have a "theory of mind," or understanding of the mental lives of others. The results give little grounds for confidence about chimp empathy. For example, the animals did not grasp that it would be more productive to beg for food from humans who could see them than from those who could not see them (because the humans were blindfolded or had buckets over their heads).

In other experiments, scientists have used mirrors to test animal self-awareness. Unlike most species, chimps seem to know that they are seeing themselves in a mirror; chimps that have been marked on the ear or brow with a dye tend to touch those areas when shown their own reflections. Similar claims have been made for orangutans and dolphins. (The experiment is much harder with a dolphin.) Wynne, however, points out considerable ambiguities in such research. Animals may perceive reflections as members of their own species. And in humans with conditions such as autism and prosopagnosia, there is no clear correlation between recognizing a reflection and having a sense of self.

Wynne presents a nuanced picture of dolphins that veers notably from the romantic view held by many people. In some respects, dolphins match their benign stereotype (aiding drowning swimmers, for instance), yet their sexual relations are violent and coercive. Dolphins have larger brains than humans, but their density of nerve cells is far lower. Their characteristic whistles seem to be a limited form of communication, not comparable to human language. Overall, there is little basis for the sweeping claims about dolphin intelligence made by the late scientific polymath John Lilly (who, among other things, gave LSD to the animals and suggested they be represented at the UN).

What about animal rights? The expansive view of animal intelligence helps drive efforts such as the Great Ape Project, aimed at extending legal personhood and a "community of equals" to chimps, gorillas, orangutans and bonobos. Wynne aptly notes that such thinking tends to overlook the capacity of apes to harm each other and humans, and that there is little discussion of "animal responsibilities." He also explains the misleading nature of statements that, say, humans and chimps share 98.4 percent of their DNA; such measures overlook differences in how the genetic material is organized.

Recognition of the limits of animal intelligence does not preclude a concern with animal welfare. Wynne correctly points out some of the conundrums of attempting to help animals; rescuing a cat, for instance, can mean dooming various birds and mice. What these show, though, is not that reducing animal suffering is hopeless (Wynne's discussion here is a bit too pessimistic) but rather that there are choices and tradeoffs to be made. Different kinds of animals merit different degrees of consideration -- precisely what is denied in the contemptible animal-rights slogan that "a rat is a pig is a dog is a boy."


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