Alan Kamil, PhD, is a trained psychologist who spent the first 25 years of his career working in a psychology department, but if you ask him what he does for a living, he'll tell you he's a biologist.

He hasn't discarded his psychology roots by any means, he emphasizes. But he believes "biologist" better represents his persona and research, which probes animal cognition from an evolutionary perspective.

In taking a more biological slant in his work, his focus has shifted from whether species differ in their cognitive abilities--the main emphasis of much of comparative psychology--to how and why each species developed its particular set of cognitive skills. By studying cognitive tasks that are ecologically valid to animals in nature, he can directly apply his findings to understanding animal evolution.

"My background in psychology has been extremely valuable, but biology has focused the attention of my research on more interesting and important questions," says Kamil, who has worked in the University of Nebraska's biology department for the past seven years.

He contends that more comparative psychologists should become better biologists to truly make progress in understanding animal cognition. In fact, as many biologists become more like psychologists in their research methodology--using strong controls and powerful statistics--they are beginning to infiltrate the domain previously dominated by comparative psychologists and could take it over unless psychologists are also ready to move more toward the middle.

"Unless we take evolutionary biology more seriously and the contributions we can make using evolutionary biology, animal cognition will simply migrate from psychology to biology," says Kamil. "We're studying psychological processes as they are manifested in biological systems. And therefore psychologists should be better biologists."

Becoming a biologist

Kamil's interest in biology began in the early 1970s, a few years into what became a 25-year tenure at the University of Massachusetts at Amherst. As a comparative psychologist, he was primarily interested in animal learning and how it might differ between species.

For eight years, Kamil tested blue jays' abilities to learn "learning-set"--a technique developed by Harry Harlow, PhD, in which animals learn to solve new problems very quickly, a kind of "learning to learn," as it is sometimes called. Kamil found that blue jays learn the task the same way rhesus monkeys do--they don't learn quite as well as the monkeys, but they show the same patterns of learning, memory and transfer.

In fact, he discovered, blue jays are more similar to rhesus monkeys in the way they learn learning-set than are spider monkeys, cats or pigeons. That puzzled him because, in evolutionary terms, blue jays should be more similar to pigeons than rhesus monkeys, and spider monkeys more similar to rhesus monkeys.

"The question then became, 'What else is there?' And it's at that point that I really started to become a biologist," says Kamil.

He reasoned that he couldn't figure out why certain species were good at learning-set while others were not because he didn't know the relationship between learning-set as studied in the laboratory and the skills the animals use in real life. And because learning-set was contrived by researchers, he abandoned the task and began to look for one that was more ecologically valid--concerned with what animals do in the wild.

"I started reading books about animals in nature and taking courses in the biology department," he says.

One biology class turned him on to cryptic prey--animals that use camouflage to avoid detection--and the animals that hunt them through visual searching. In many of these predator-prey systems, the prey develop different forms or "polymorphisms"--that is, the same species develops into three or four types that differ in their appearance.

Kamil became interested in how the cognitive characteristics of predators--for example, the mechanism they use to search for prey--might influence the evolution of prey. Biologists knew that prey populations tend to stabilize with relatively constant numbers of the different "morphs" or types.

One explanation for this, proposed by biologist Luuk Tinbergen, PhD, in 1960, is that after an animal successfully locates the same hard-to-find search pattern--or prey type--several times in a row, that pattern becomes easier to find. So as the density of a prey type increases, the likelihood that the hunter would encounter it several times in a row would increase. That in turn increases capture of that prey type and allows the population of other prey types to increase. But in 1973, when Kamil first heard this theory, no one had tested it rigorously.

"Most of the published studies were terrible, with no proper controls," says Kamil. "So testing this theory intrigued me because I thought it was probably a psychological process of some interest."

Putting it to the test

To conduct the testing, Kamil and his colleagues designed a laboratory technique in which they showed blue jays photos of underwing moths--cryptic moths that closely resemble tree bark. If the jays detected a moth, they pecked a key depicting a moth. If they didn't detect a moth, they pecked a blank key.

Findings from this research were the first to validate Tinbergen's theory that the more exposure the jays have to a particular moth morph, the better they become at detecting that morph. And they served as a first step toward understanding how the cognitive abilities of a predator might influence the evolution of its prey.

Most recently, Kamil and University of Nebraska colleague biologist Alan Bond, PhD, have developed computer versions of cryptic moths. To see whether these digital moths were good approximations of real moths, they tested blue jays' ability to detect them and compared the results with their earlier work with photographs.

In fact, the jays responded in the same way as they did to the photographs--improving their detection of a particular morph the more exposure that they had to it. They also found that as the jays' ability to detect one type of prey increased, their ability to detect other morphs decreased, suggesting that the birds' cognitive abilities allow them to maintain selective attention for only one morph at a time.

Most recently, Kamil and Bond have entered into what they call "virtual ecology," in which they use their digital moths to create a virtual population that can evolve based on "predation" by blue jays. They've found evidence for the theory that polymorphisms are maintained by predators' search patterns. Because of blue jays' tendency to locate the type of moth that is most prevalent in the population, the more common a moth morph becomes, the more likely it is to be detected and removed from the population. Then, as the population of that morph declines, another morph becomes most prevalent and the cycle starts anew, find Bond and Kamil, who published the study in 1998 in Nature (Vol. 395, p. 594­596).

"We've come to realize that if you want to understand the evolution of different kinds of prey," says Kamil, "you have to understand the psychology of the predators: how they learn, their perceptual and sensory capabilities, the rules of associative learning."

The work on the evolution of cryptic prey on which Bond and Kamil are collaborating is particularly satisfying, Kamil believes, because it allows him to apply his interest in animal cognition to ecologically valid problems. The findings can be directly applied to understanding animal evolution and co-evolution.

Studying animal cognition without evolutionary ideas "is as hopeless as the study of animal cognition without the knowledge of associative learning," says Kamil. "When we study cognition, we're studying the output of a biological system. But it's biological not just because it's neurons and blood and guts. It's also biological in that it's highly evolved."