Foundations of Evolutionary Psychology

Charles Crawford, Dennis Krebs

• Publisher: Psychology Press
• Year: 2012
• eBook ISBN: 9781135704148
• Topic: Psychology
• Subtopic: Experimental Psychology
• Index: Psychology

Evolutionary psychology is concerned with the adaptive problems early humans faced in ancestral human environments, the nature of the psychological mechanisms natural selection shaped to deal with those ancient problems, and the ability of the resulting evolved psychological mechanisms to deal with the problems people face in the modern world. Evolutionary psychology is currently advancing our understanding of altruism, moral behavior, family violence, sexual aggression, warfare, aesthetics, the nature of language, and gender differences in mate choice and perception. It is helping us understand the relationships between cognitive science, developmental psychology, behavior genetics, personality, and social psychology.

Foundations of Evolutionary Psychology provides an up-to-date review of the ideas, issues, and applications of contemporary evolutionary psychology. It is suitable for senior undergraduates, first year graduate students, or professionals who wish to become conversant with the major issues currently shaping the emergence of this dynamic new field. It will be interesting to psychologists, anthropologists, sociologists, economists, philosophers, cognitive scientists, and anyone interested in using new developments in the theory of evolution to gain new insights into human behavior.

1

Evolutionary Psychology

The Historical Context

CATHERINE SALMON AND

CHARLES CR AWFORD

“In the distant future I see open fields for far more important researchers. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.”

Charles Darwin, 1859, On the Origin of Species

One such new field is Evolutionary Psychology. This discipline focuses on the study of human behavior from an adaptationist perspective, examining the mental mechanisms that evolved to solve problems faced in our ancestral past and how those mechanisms continue to produce behavior today. There are several peer review journals that focus specifically on this field, including Evolution and Human Behavior and Human Nature; ones that focus mainly on this field, including Evolution and Cognition and Politics and the Life Sciences; and many others that regularly publish articles from this perspective including Behavioral and Brain Sciences, Journal of Personality and Social Psychology, Animal Behavior, Quarterly Review of Biology, and Cognition. This chapter will describe the historical antecedents of the evolutionarily informed study of human behavior.

Evolutionary Thinking Before Darwin

For much of our recorded history, and perhaps long before, people have been fascinated with the natural world and our place in it. The complexity of our own nature, both physical and mental, has been a source of particular interest. How could something as complex as a person come into existence if not by the hand of God? In the eyes of many, such complexity (epitomized by the human eye) seemed to require special design, which implies a designer. The idea that all of nature, including man, was created as it is by an omnipotent power has been a wide-ranging belief, formalized in religious doctrine. Aristotle contributed to this belief with “The Great Chain of Being,” the idea being that each species had its own particular place in a hierarchical progression. God was at the top of the ladder (true perfection), followed by angels, men, women, animals, plants, and inanimate objects. The implication is that there is a natural order to things, something or someone cannot move from one rung of the ladder to another.

But not all pre-Darwin thinking about human origins was quite so creationist. Plato (as cited in Davis, 1849), for example, suggested, in discussing the ideal society, that

It necessarily follows … from what has been acknowledged that the best men should as often as possible form alliances with the best women, and the most depraved men, on the contrary, with the most depraved women; and the offspring of the former is to be educated, but not of the latter, if the flock is to be of the most perfect kind … As for those youths, who distinguish themselves, either in war or other pursuits, they ought to have rewards and prizes given them, and the most ample liberty of lying with women, that so, under this pretext, the greatest number of children may spring from such parentage. (p. 144)

Plato was making not only moral statements but genetic ones as well. Of course, animal domestication and breeding had been going on among early hunter-gatherers. As far back as 15,000 BC, dogs and sheep were shaped through a combination of natural selection and selective breeding by humans. Plato applied the same thinking to humans, suggesting that moral qualities could also be bred for selectively in order to produce a more ideal society.

The 1700s were a century in which many ideas about evolution were proposed, most characterized by a belief in progress. Condorcet argued that man’s history illustrated movement from lower to higher states. Humans developed from primitive savages through increasing enlightenment, and ultimately, they would reach perfection. Lyell, focusing on the earth rather than people, claimed that the land and seas acquired their current form gradually through a series of causes or events that continue to operate and can be observed. German philosopher Immanuel Kant (1798/1998) suggested that other primates might develop the mechanisms for walking and speech, to evolve the capacities of man including reason. Erasmus Darwin proposed that all living things could have emerged from a common ancestor, with competition the driving force. Lamarck argued for the inheritance of acquired characteristics as a mechanism of evolution. And, Thomas Malthus, an Anglican clergyman, published an essay on population that helped set Charles Darwin on the road to developing his theory of evolution by natural selection. Malthus wrote that populations of organisms grow exponentially, while natural resources increase arithmetically. What this means is that population growth exceeds the growth of resources required to maintain the entire population. Thus, individuals will inevitably compete for survival.

Malthus used his theory to argue for a variety of measures to keep the human population under control. It took Darwin and Wallace to realize that Malthus had provided a basis for understanding how species are formed and how they change. Their insights led to the reading of On the Tendency of Species to Form Varieties and On the Perpetuation of Varieties and Species by Natural Means of Selection at the Linnaean Society and the publication of Darwin’s book, On the Origin of Species by Means of Natural Selection, in 1859.

Darwin’s Insights

In 1858, Darwin and Wallace’s ideas were proposed at a meeting of the Linnaean Society. The paper that was read claimed that evolution occurs because of “natural selection.” As evidence, they offered studies of comparative morphology and fossil records. They proposed a mechanism for evolution, natural selection. They used as an analogy the artificial selection used in the breeding of domestic animals, except that in the case of natural selection, it was the environment that shaped species, not the individuals doing the breeding. The two components that are essential to the process of natural selection are (a) heritable variation (i.e., individuals in a population differ from each other and some of that difference is heritable) and (b) differential reproductive success (i.e., some individuals, because of their differences, are better able to survive and reproduce than others are). In the world Malthus described, of individuals in competition for available resources, it is easy to see how heritable variation that improved one’s chances to utilize such resources, in comparison with other individuals, would increase in the next generation. Those variations that were helpful would spread, and those that were not, would die out.

This was the essential nature of the argument. To use the giraffe as an example, if giraffes with longer necks than the average were slightly more successful at feeding from the tops of trees than giraffes with average necks, they would grow and survive better than other giraffes and be more successful at reproducing as well. Their offspring, who would share their slightly longer necks, would increase proportionately in the population of giraffes. Over time, the distribution of neck lengths would shift due to the reproductive advantage held by those with longer necks.

It is important to remember that natural selection is not just about the differential ability to survive. If traits are to be passed on, reproduction must also occur. All species overproduce offspring, not all of which can survive to reproduce themselves. There is, as a result, competition within a species for the means to survive and to reproduce, and any advantage at either task will be naturally selected.

Because most traits are passed on from parent to offspring and are modified over time based on their ability to help their possessors deal with the environment, there is an emphasis on descent in Darwin’s writing. Each species has descended from earlier species, and its characteristics (e.g., opposable thumbs) must be understood in the context of their origin in earlier species. When we consider the evolution of humans, we ask how the hominid line has descended from earlier primates and how the hominids in our direct line, such as Homo habilis and Homo erectus, gave rise to Homo sapiens. Because the great apes are descended from a primate ancestor that also gave rise to the hominid line, their anatomy, physiology, and behavior is of value for understanding our human characteristics. The Descent of Man closes with the following:

Man with all his noble qualities, with sympathy that feels for the most debased, with benevolence which extends not only to other men but to the humblest of living creatures, with his god-like intellect which has penetrated into the movements and constitution of the solar system—with all these exalted powers—still bears in his bodily frame the indelible stamp of his lowly origin. (p. 405)

The outraged response to Darwin’s theory is well known. In what is probably the most famous account, during a debate at Oxford, Bishop Samuel Wilberforce asked Huxley whether he claimed descent from monkeys on his mother’s and father’s side. Huxley (1900) replied that he would rather be descended from an ape than to have as an ancestor a man who would debate such a serious matter with such mockery.

Darwin believed that his theory could account for all aspects of human evolution. Wallace, the codiscoverer of natural selection, could not accept that the evolution of the human brain, in all of its complexity, could be explained by natural selection or that the same principles that explained the evolution of human anatomy could also explain human mental evolution. For some, this is still a controversial issue. Wallace eventually turned to spiritualism and religion for his answer to the design of the human brain.

One thing that puzzled Darwin, was the presence of structures that seemed unrelated to survival, the most famous being the brilliant plumage of the peacock’s tail. There is obviously a metabolic cost to producing such a tail, and it is a walking advertisement of a meal for predators. If there is no survival benefit, how could natural selection explain it? Darwin also noted that in some species males and females are dramatically different in size and possess quite different features (e.g., the peacock’s tail). Why such differences when males and females face the same problems of avoiding predation and finding food?

Darwin’s answer was his theory of sexual selection, which he envisioned as a second theory of evolution. Darwin saw natural selection as focusing on adaptations that came about because of competition to survive while sexual selection focused on adaptations that were the result of competition for reproductive opportunities. He suggested that sexual selection could take two forms: (a) intrasexual competition and (b) intersexual selection. Intersexual competition is competition between members of the same sex where the outcome contributes to matings with the other sex (to the victor go the spoils). Typically, a male will gain sexual access to females directly as a result or by controlling territory or resources that females desire. The loser in the competition will typically fail to mate. Whatever traits lead to victory (e.g., size, strength, etc.) will be passed on through the mating success of the winners while the losers’ qualities will fail to be transmitted.

The second method of sexual selection is intersexual selection or mate choice. If there are qualities that are valued by one sex in a mate, then individuals of the opposite sex possessing those qualities will be preferentially chosen as mates. Those that lack those qualities will not get mating opportunities. Over time, those qualities desired in a mate will increase in frequency. Darwin called this female choice because he had noticed that in a majority of animal species, the females are choosy about the males with whom they mate. Though Darwin believed natural and sexual selection were two different evolutionary processes, we now know they are part of the same basic process of differential reproductive success because of heritable differences in design. But keeping both terms reminds us of the usefulness of distinguishing between adaptations that are the result of survival advantages and those that are the result of advantages in attracting a mate.

In The Descent of Man and Selection in Relation to Sex, Darwin (1883) not only applied his theory of natural selection to human evolution and detailed his theory of sexual selection; he also discussed his thoughts on human faculties such as love, sympathy, beauty, and morality. He argued against making a distinction between mind and body and suggested that we shared many aspects of our human faculties with other animals. He stated, “[N]evertheless the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind” (Darwin, 1883).

Darwin (1980) elaborated on his ideas about the evolution of human and animal emotions in The Expression of Emotion in Man and Animals. In it, he suggested that the process of evolution by natural selection applies not only to anatomic structures but also to the “mind” of an animal and to expressive behavior. He believed that facial expression developed as a mechanism of communication and that there are specific inborn emotions with a specific pattern of activation of facial muscles and behavior in response to each emotion. Today, emotion researchers, such as Paul Ekman (Ekman & Davidson, 1994), continue in this tradition, exploring the cross-cultural functions and expression of various emotions,

The Early Enthusiasts
(Darwin’s Influence on Nonpsychologists)

While much attention has been paid to early opposition to Darwin’s views, there were many who took inspiration from them. Throughout history, people have sought explanations and justifications for moral order in the world. We mentioned Plato’s views on this earlier. Since the theory of evolution by natural selection provided an explanation for the origin and shape of life on earth, some wondered if it might help provide an explanation for the nature of society and even a blueprint for the type of society that human beings should strive to create.

British philosopher Herbert Spencer was an important advocate of using evolutionary theory to understand human social organization. He coined the phrase “survival of the fittest,” which is often attributed to Darwin, and he wrote many articles and books on how evolutionary theory could help create an ideal society. He saw evolution as a moral force that would bring human society from the primitive to a modern democratic industrialized state. For this to happen, he argued, free competition between individuals must be allowed and encouraged, and interference from outside sources (e.g., government) should be avoided. Those individuals or businesses unable to cope, should be allowed to fail, propping them up would weaken society. Nature must be allowed free rein to select the strongest, the result being a continuously improving society. This type of thought was typical of what became known as “Social Darwinism.” It can, one can imagine, can be taken to unpleasant extremes. It has been used to argue for the support of imperialism, the subordination of women, and the existence of the social class system. In an address to a children’s Sunday school, John D. Rockerfeller said, as cited in Crawford, 1979, p. 260, “The growth of a large business is merely a survival of the fittest … it is merely the working out of a law of nature and a law of God.” Of course, it has also been taken to greater extremes by individuals such as Adolf Hitler, using such a model to justify the extermination of those he considered unfit in his quest to purify the German people and create his own ideal society.

McDougall in the United Kingdom and William James in the United States both studied what are referred to as instincts, defined as the inherent disposition of an organism to behave in a particular way. The idea was that instincts are unlearned inherited patterns of response or reaction to certain kinds of stimuli. An example would be an infant sucking at a nipple. James is often referred to as the father of U.S. psychology, publishing his Principles of Psychology in 1890. In particular, he outlined instincts such as fear, love, and curiosity as driving forces of human behavior, suggesting that humans may possess more instincts than other animals do.

Another early psychologist, James Mark Baldwin (1896), was fascinated by the question of how a process like natural selection could produce an organism with the creative capacities of the human mind. His answer was called the Baldwin Effect, though ethologist Morgan and paleonto...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright
• Contents
• Preface
• About the Editors
• Contributors
• 1. Evolutionary Psychology: The Historical Context
• Part I: Biological Foundations of Evolutionary Psychology
• Part II: Development: The Bridge from Evolutionary Theory to Evolutionary Psychology
• Part III: Evolved Mental Mechanisms: The Essence of Evolutionary Psychology
• Part IV: The Evolutionary Psychology of Sex Differences
• Part V: The Evolutionary Psychology of Prosocial Behavior
• Part VI: The Evolutionary Psychology of Antisocial Behavior and Psychopathology
• Part VII: Exploring the Explanatory Power of Evolutionary Psychology
• Author Index
• Subject Index