Science Literature

In The Descent of Man, Charles Darwin argued that there is "no fundamental difference between man and the higher mammals in their mental faculties". To support this claim, he drew attention to cases where precursors of human intelligence could be found in animals, including "similar passions, affections, and emotions, . . . [such as] jealousy, suspicion, emulation, gratitude and magnanimity". This approach has spawned numerous research projects to further Darwin's agenda.

"Over the past two decades, researchers have reported that chimpanzees can empathize with other members of their species, and that they reconcile and even console each other after conflicts. Monkeys and apes have been credited with a sense of fairness and aversion to inequity and, in the case of apes, an awareness of the mental states of others - in other words, a theory of mind."

This chimp has something to smile about (Source here)

There has been a major problem, however, with establishing suitable control conditions. Furthermore, many researchers have not been objective analysts, but have indulged in "a flurry of anthropomorphic overinterpretation". In an excellent essay on these matters, Bolhuis and Wynne provide a healthy check on these enthusiasms.

"For instance, capuchin monkeys were thought to have a sense of fairness because they reject a slice of cucumber if they see another monkey in an adjacent cage, performing the same task, rewarded with a more sought-after grape. Researchers interpreted a monkey's refusal to eat the cucumber as evidence of 'inequity aversion' prompted by seeing another monkey being more generously rewarded. Yet, closer analysis has revealed that a monkey will still refuse cucumber when a grape is placed in a nearby empty cage. This suggests that the monkeys simply reject lesser rewards when better ones are available."

Bolhuis and Wynne point out several behaviours and skills displayed by birds which have been interpreted in anthropomorphic ways when seen in apes and monkeys. They suggest that evolutionary convergence may be more important than ancestral relationships. They point out that many researchers have laboured hard at teaching apes some form of language, but "linguists generally agree that the resulting efforts made by chimps and bonobos don't qualify as language". When it comes to copying sounds, birds are often "striking vocal mimics". This allows them to give their first summary statement:

"The appearance of similar abilities in distantly related species, but not necessarily in closely related ones, illustrates that cognitive traits cannot be neatly arranged on an evolutionary scale of relatedness."

The second issue addressed concerns the factors that drove the "emergence of contemporary animal and human traits". These drivers are not amenable to leaving traces in the fossil record. Consequently, this whole field is wide open to the import of assumptions. They give an example: the idea that "our modern skulls house a Stone Age mind". They stress that this is an assumption, not a conclusion.

Thirdly, they point out a methodological problem in the way evolutionary analyses have been employed. If researchers want to find the cause of a particular behavioural trait, why use a methodology that traces the course of history? Failure to appreciate this mismatch has led to countless cases of Darwinian storytelling based on speculations about adaptation.

"Questions about the causal underpinnings of behavioural differences can be elucidated only with a causal analysis, not through reconstructing evolutionary history."

The essay closes with an appeal for more empirical research and less "naive evolutionary presuppositions". Any evolutionary interpretation must be "verified using controlled experiments". Those who claim that nothing in biology makes sense except in the light of evolution need to bite their tongues and realise this approach has promoted unhealthy science. If Darwinism at any level is to survive, it must be underpinned by empirical research, not imported as theoretical baggage or added on as an intellectual gloss.

"We are not suggesting an abandonment of Darwin's insights. Rather, we call for care in their application. When reconstructing the evolutionary history of cognitive traits, there is no a priori reason to assume that convergence will be more important than common descent or vice versa. In addition, evolutionary theory may suggest hypotheses about the mechanisms of cognition, but it cannot be used to actually study these mechanisms."

This essay is a useful contribution to thinking about the cognitive abilities of animals and humans. Very refreshing! For more blogs on human traits, go here and here.

Can evolution explain how minds work?
Johan J. Bolhuis & Clive D. L. Wynne
Nature, 458, 832-833 (16 April 2009) | doi:10.1038/458832a [restricted access link]

Abstract: Biologists have tended to assume that closely related species will have similar cognitive abilities. Johan J. Bolhuis and Clive D. L. Wynne put this evolutionarily inspired idea through its paces.