Evolutionary Psychology Has Wide Ranging Implications

I usually devote this column to interesting research from our Department. This time I want to talk about a book on a new branch of psychology that some of us have become interested in lately. The Moral Animal, by Robert Wright, is about the science of evolutionary psychology. Evolutionary psychology begins with the idea that each species on Earth owes most of its characteristics to evolution by natural selection. From generation to generation, natural selection causes those characteristics that contribute to successful reproduction to increase their representation in succeeding generations.

Similarly, characteristics that impede successful reproduction disappear. Of course, the selection occurs at the gene level: genes are selected for their contribution to successful reproduction. And reproduction isn't just producing offspring; it includes having offspring grow to maturity to have offspring of their own, and on and on.

Scientists universally accept the theory of evolution nowadays though they argue about the details. It's much like the atomic theory of matter: scientists all agree that matter is composed of atoms, but argue about the details of atomic structure. It's especially interesting to apply evolution to humans. It's easy to see how evolution formed our bodies: the (reproductive) advantages of big brains, opposable thumbs, and upright stance are fairly obvious. Evolutionary psychology theorizes that natural selection also formed the human mind. The idea is that we have the emotions, perceptions and thinking abilities we do because they were reproductively advantageous to our ancestors. Evolutionary psychologists make a persuasive case that human tendencies towards aggression, jealousy, competition, cooperation and altruism are all largely due to the natural selection that operated on our ancestors.

The idea that an emotion or thinking pattern was produced by evolution might seem strange at first. But one can see how some of our feelings must have evolved. For example, thousands of years ago, any humans who weren't attracted to fertile members of the opposite sex, who didn't find sexual intercourse pleasurable, and who didn't love, feed, and protect their children would have few descendants around today.

Thus, everyone alive today is descended from people who were attracted to the opposite sex, did enjoy sex, and did love their children. No one has to teach us these things; we inherit them. By the same token, we are all the descendants of humans who (to name a few examples) cooperated with their friends and relatives, competed with other people, taught their children how to survive, tried to ensure their mates were faithful, and strove for status. The operation of evolution over thousands of generations means that humans feel love for mates, children and friends. But evolution has also given us guilt, jealousy, envy, competitiveness, and even hatred because, under some circumstances, these feelings once conferred a reproductive advantage.

This thinking sometimes runs contrary to modern social science which often assumes that most of our mental makeup is due to our cultures. Evolutionary psychology gives less weight to culture as a source of human differences, but doesn't deny it. It's obvious that the human brain is a powerful learning machine, but, according to evolutionary psychologists, natural selection has had a strong influence over what it is easy for the brain to learn.

A good example of this is language. All humans use language and all healthy children learn to talk fluently though no one formally teaches them. We inherit our ability to learn and use language because it conferred a tremendous advantage to our ancestors -- language ability is the product of evolution. The particular language (English, Hindi or Pidgin) we speak is determined by the people around us as we grow up -- our culture. This language example points out another important thing about evolutionary psychology: people were the source of most of the natural selection that designed our minds -- minds designed to solve social problems. Language's great advantage is the ability to influence the behaviour of other people, for example.

The title of the book made me suspect that Wright would argue that those human characteristics that evolved must be the morally correct ones, essentially that we should view aggression and competitiveness as inevitable, acceptable and even desirable facets of human nature.

Rather, Wright argued that our ability to make moral judgments also evolved and that we should not be afraid to use it. In making moral judgments we must understand, however, where our thoughts, feelings, and attitudes came from.

This big theory leads to a modest theory of our own that we want to pursue in future work. What about psychopaths? Psychopaths are people who seem to care little for others. They seem to be completely asocial. How could evolution explain such people? I'll write more about this question next time.