What Do Rats Prove?

Psychologists and other social scientists study the actions and reactions of the albino rat to learn about human behavior. Now a University of Wash ington psychologist, Robert B. Lockard, suggests in American Psychologist that the laboratory lessons may be invalid, and that the rats do not prove much about people. The reason is that the albino rat--a mutant form of the wild brown rat--is a genetic monster of dubious value to research. Caged and bred in captivity for more than a century, it is a man-made abomination--fat and degenerate, faithful neither to its wild ancestry nor to its laboratory role as a distorted mirror of man. "Theories are tested upon it," says Lockard. "Students are trained with it, and generalizations are based upon it. If albinus is misleading, so are many of the products of psychology."

Across the Volga. According to Lockard, several factors disqualify the rat as an experimental animal. The first is that the laboratory rat, originally Rattus norvegicus and an indigene of Asia, crossed the Volga River into Europe only 250 years ago. On history's ample scale, it is a newcomer; its rapid diffusion, combined with rapid breeding, makes of the Norway rat an animal that is still in violent evolutionary motion. To arrest it, as in the laboratory, says Lockard, is to claim validity for a motion-picture still.

Moreover, the laboratory animal and the wild animal now bear little resemblance to each other. They are both rodents, but that is about all. Confined in thousands of laboratories, the white rat represents hundreds of different varieties, each as different from its common ancestor as the Chihuahua is from the wolf. Some cornered Norway rats will fight to the death rather than allow themselves to be captured by a man; a cornered laboratory rat will simply back away. Wild Norways ruthlessly kill intruder rats; their amiable laboratory cousins merely sniff at strangers. Wild rats survive by their wits; captive rats can and do survive as near idiots. On the other hand, it is possible that the laboratory has produced a strain efficient in disentangling its toes from 1/2-in. wire mesh--definitely a survival factor in captivity.

With unwarranted assurance, psychologists have frequently extrapolated from rat performances in mazes all manner of conclusions about man. Because rats can tolerate a good deal of alcohol, for instance--ounce for ounce, more than man--experimenters have thrown doubt on the longstanding conclusion that man and drink dangerously mix. Insights into the human capacity for stress, based on experiments with placid laboratory rats, falter before the unrehearsed wild rat's total inability to endure any man-imposed stress at all.

Dependent Animal. In its social organization, the rat makes a poor human analogue. The newborn rat, for instance, gets a minimum of parental care and is self-sufficient within just 22 days. The young human is the most cared-for of all the world's mammals. His dependency can last as long as 22 years.

Why the rat anyway, with so many better possibilities around? As one possible successor, Lockard proposes the oriental tree shrew, which is readily tamed, breeds promiscuously throughout the year and, on the evolutionary map, lies nearer to man than does the rat. To focus on the rat, when less than 1% of all species has ever been impounded in a laboratory, says Lockard, is like examining only the earth and then generalizing about the universe.

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