Illustration: Joe Kloc
A study published last month in the Proceedings of the National Academy of Sciences found rooks—a type of crow—were capable of making and using tools to solve puzzles and obtain food. A closer look at the questions raised by the study illustrates the difficulties facing cognitive scientists as they try to tackle one of the central questions of their field: How did animal minds—both human and nonhuman—evolve?
In the rook study, researchers Christopher Bird and Nathan Emery from the University of Cambridge filmed the birds bending a metal wire into a hook shape in order to fish a food-filled bucket from the bottom of a plastic tube. According to Bird, one of the most significant aspects of the study is that the rooks were not trained to build tools, yet they were able to successfully do so in many cases on their first attempt. “This suggests that they are using insight or rapid learning to solve these problems,” he said.
In many respects, Bird and Emery’s study mirrors that of Oxford behavioral ecologist Alex Kacelnik, which showed in 2002 that a New Caledonian crow named Betty was capable of solving similar problems that required her to manufacture tools. But, says Bird, what distinguishes the two studies is that New Caledonian crows use tools in the wild and rooks do not. “Scientists have speculated that tool use was just an adaptation of the New Caledonian crow,” he says. “But finding that rooks can do it as well seems to suggest that it is a capacity of the whole corvid family.”
When only New Caledonian crows were known to make tools, it was thought that they evolved the ability because of ecological pressures—perhaps in order to exploit a food resource they could not otherwise access with their beaks. But Bird is suggesting that the rook study is evidence that New Caledonian crows—and all corvids—may have inherited the ability from a common ancestor.
But determining whether two species share a trait because they have a common ancestor or because they face similar ecological pressures poses a particular set of difficulties when that trait is a cognitive ability. “Studying the evolution of these things is almost a lost cause because we’re never going to have any fossils,” says Clive Wynne, a behavioral psychologist at the University of Florida. The mind leaves no physical record; no sand-covered fossilized fMRI scans of early man or corvid or chimpanzee for scientists to set out on a table and use to chart a cognitive history. As a result, Wynne goes so far as to question whether common ancestry can even be considered when studying the evolution of the mind. “I’m not saying some cognitive abilities did not evolve,” he explains. “I’m just saying that without fossils, all we have to look at is the species that exist today as they exist today and so we simply cannot know when we are looking at common descent.”
Wynne and his colleague Johan Bolhuis of Utrecht University in the Netherlands published an essay, which bore the provocative name “Can evolution explain how minds work?” in an April issue of Nature in which they also argue that in the case of humans, a common descent-focused approach to understanding the evolution of the mind discounts the importance of cultural influence.
But many—if not most—don’t share Wynne’s views. Wynne and Bolhuis’ essay drew a flurry of mixed responses published in Nature and elsewhere.
Illustration: Joe Kloc
Most critics are fired by the success of the evolutionary perspective. Kacelnik, who studied the New Caledonian crows, cites the view of evolutionary biologist Theodosius Dobzhansky that biology only makes sense in light of evolution. According to Kacelnik, “Wynne is calling for, in a sense, an abandonment of the evolutionary perspective. And that’s the last thing we ought to do.” He says that molecular evidence from DNA can be used in place of fossils in order to determine whether a behavioral trait shared between two species is the result of them having a common ancestor. In an essay published online last week in PNAS, Kacelnik also responded to Wynne by pointing to recent studies of the differences in cognitive abilities between human and nonhuman apes as evidence that “the straightforward application of Darwinism seems like a better idea day by day.”
Some are probably motivated by the support that Wynne has been getting from unscientific quarters. Creationists have used the essay to bolster their arguments for a Genesis-style creation of the mind—undoubtedly only further fueling scientists’ reactions.
“That’s not our point at all,” Wynne says, referring to his creationist fans. Wynne, instead, is serving as a severe internal critic of comparative cognitive studies, a sort of necessary resistance to the way comparative psychology is practiced today. He contends that the field has largely grown “willfully non-analytic,” referring to the ambiguity of behavioral categories such as tool use.
“We can only expect to make sense of the evolution of a trait if our description of it is well grounded,” Wynne says. He suggests that it might not make sense at all to study the evolution of tool use—at least as we have defined it. His point is that many animals may have evolved all the cognitive abilities necessary to use tools without ever displaying any behavior that fits our definition of tool use. For example, pigeons have been shown to press buttons in order to obtain food, and while button pressing might not fall into the category of tool use, it may still be a result of applying the same cognitive abilities. Thus it is these underlying abilities on which researchers should be focusing.
“It’s a tough nut to crack,” says Edward Wasserman, a comparative psychologist at the University of Iowa. A good deal of research in animal cognition has a “gee-whiz flavor,” he says, but it fails to get at the behavioral or cognitive processes involved. The “gee-whiz flavor” that Wasserman is talking about is the anthropomorphic language researchers and journalists deploy to describe nonhuman animal behavior. The rook study, for example, dubbed the rooks’ behavior as both “insightful,” and “creative.” “What is clear to me is that such notions as insight and creativity provide no useful interpretation whatsoever and are akin to invoking magic,” Wasserman says. Or as Wynne puts it: “What the hell does insight mean?”
In his essay in PNAS, Kacelnik writes that using insight to explain certain animal behavior is “as baffling as the problem that [it] is supposed to solve.” And even with regards to humans, the concept of insight is not clearly understood.
The prevalence of human descriptions of behavior in animal cognition studies can perhaps best be understood as a hazard of a field that brushes so closely with questions about the human mind. When an animal displays behavior that appears similar to our own—such as creativity, insight, or envy—it may be more comfortable to describe it on our terms than to search for its underlying causes for fear that finding them might make us a little less human.
Studying how minds evolve is a sticky business, where disagreements over everything from word choice to the limitations of what is knowable leave us to wonder if we’re even asking the right questions. (As Wynne might say, What the hell does mind mean?) But if anything can be taken from the romantic language, apparent contradictions, unproven theories, and the personalities that debate them, it is that understanding how minds evolve is a most human endeavor.
Originally published June 25, 2009