Human Evolutionary Psychology

At least since the emergence of sociobiology in the 1970s, attempts to interpret human behavior within an evolutionary framework have met with spirited resistance. Opponents of this approach fall into two camps. One camp comprises the Creationists, who deny the facts of evolution. Although these “intelligent design” advocates have been politically influential, they are not taken seriously by reputable biologists. The other camp includes scientists who question whether the evolutionary framework provides much in the way of testable hypotheses about human psychology. While sometimes criticizing the evolutionary approach from a quasi-Marxist perspective, these critics have emphasized that their objections are scientific as well as political. In a welcome departure from the polemics that have so often blurred the issues, Barrett, Dunbar, and Lycett have written a dispassionate and authoritative review of the scientific achievements and limitations of this field.

The authors note that the evolutionary framework includes two distinct research traditions: human behavioral ecology and evolutionary psychology proper. Their own work lies chiefly in the first tradition, and the book reflects this emphasis. An important goal of this book is to show how the two approaches complement one another.

The authors spend the first two chapters dispelling common misconceptions about Darwinian approaches to human behavior (e.g., that it constitutes a form of “genetic determinism”) and reviewing basic concepts in evolutionary biology. Turning next to research in human behavioral ecology, they consider social behavior in terms of its current adaptedness (i.e., likelihood of resulting in fertile offspring). Topics traditionally addressed by cultural anthropologists (e.g., marriage and mating, altruism and cooperation, child rearing) are viewed through the Darwinian lens. They cover classic work, such as that on reciprocal altruism, as well as provide analyses of behavior seemingly inconsistent with an evolutionary account (e.g., homosexuality, adoption).

Although the book is titled Human Evolutionary Psychology, only several chapters at the end are devoted to research in this tradition. Evolutionary psychologists attempt to elucidate the evolved psychological mechanisms that mediate behavior rather than evaluating the relative fitness of the behavioral strategies per se. They seek to identify the selection pressures that have shaped human psychology throughout natural history and then to examine whether cognitive mechanisms exhibit the features one would expect if these mechanisms were indeed “designed” to solve these problems (e.g., communication, detecting cheaters in social groups, selecting mates). Because these mechanisms evolved during the long hunter-gatherer phase of human natural history, they need not mesh well with modern environments. What was adaptive throughout the evolution of the species may cause problems today.

The authors seldom mention psychopathology. One notable exception concerns their coverage of research on people with autism, who, scientists suspect, may lack an evolved theory-of-mind mechanism that enables people to take the perspective of others. Nevertheless, if human behavioral ecology and evolutionary psychology provide solid foundations for understanding behavior, they ought to be useful for psychopathologists.

There are at least two ways that an evolutionary perspective might inform understanding of mental illness. Mental disorders might arise from derangements in evolved, psychobiological mechanisms. The mechanism is adaptive; the disease afflicting it is not. Alternatively, symptoms themselves might reflect adaptations to selection pressures operative during the early history of our species. Certain common phobias, such as fears of snakes or heights, might qualify.

Human Evolutionary Psychology is an accessible guide to Darwinian approaches to human behavior. It is clearly written, empirically grounded, and nonpolemical. It will serve as an important resource for those interested in applying evolutionary concepts to psychopathology.