What is evolutionary psychology?

Introduction

Humans share with other mammals basic behaviors, motivations, and emotions, but only humans can reflect on and discuss their behaviors, motivations, and emotions, and only humans can influence the behaviors, motivations, and emotions of others through such abstract concepts as appeals to duty, religion, laws, blackmail, promises, and lies. Like other psychologists, evolutionary psychologists study the brain structures and mental functions that underlie these capacities. Unlike other psychologists, evolutionary psychologists begin with the assumption that human mental capacities evolved through natural selection
the same way that human bodies did—that is, that the brain circuitry and processes underlying thought and behavior exist because they somehow helped human ancestors to survive and reproduce. It is this perspective, rather than research topics or methodology, that differentiates evolutionary psychology from other fields and approaches in psychology.

Arguing from this perspective, evolutionary psychologists have suggested that the aspects of brain and behavior that consistently conferred the greatest advantages on human ancestors are those that are most likely to now be automatic—that is, subconscious or instinctive. People do not need to be aware of how they avoid large moving objects, for example, as long as they can do it. The corollary line of reasoning is that those aspects of brain and behavior that are now the most automatic are likely to be those that had the greatest and most consistent advantages in the past. For this reason, it is the instinctive and automatic behaviors, as well as the subconscious bases of thoughts and feelings, that have received the most attention from evolutionary psychologists.

Sensation, Perception, and Hedonic Preferences

Certain important aspects of the behavior of the physical world seem to be innately wired into, or easily acquired by, the human brain. Babies experience anxiety about steep drop-offs as soon as they can see them, without having to learn by experiencing a fall. They also flinch or move away from objects that are getting larger on a projection screen and therefore appear to be coming toward them. Although babies cannot count or do math, they very quickly appreciate such fundamental concepts as length, mass, speed, and gravity, as well as the concepts of more and less and larger and smaller. They typically acquire an easy grasp of one of the most abstract concepts of all: time.

Humans also exhibit innate preferences for things that were “good” for human ancestors and a dislike of things that were “bad.” People naturally like sweet foods that provide them with the necessary glucose for their calorie-hungry brains and salty foods that provide them with the minerals to run their neuronal sodium-pump, yet they have to acquire (and may never acquire) a taste for bitter and foul-smelling foods, which signal their brains that the substance may contain toxins. The human brain also automatically causes people to develop intense aversions
to foods that were ingested several hours before becoming ill. Even in cases when a person consciously knows that it was not that food that actually caused the sickness, the very thought of that item may cause nausea ten years after an illness.

Humans are also wired for other kinds of “taste.” Children around the world prefer parklike landscapes that provide plenty of water and trees and forms of play that provide exercise, strengthen muscles, and increase physical coordination. Adults admire the beautiful faces and shapely bodies of the young, healthy, and disease-free—those who are the safest friends and most profitable mates. In sum, experiences of pain or disgust signal that something is potentially dangerous and is to be avoided; experiences of pleasure or admiration signal safety or opportunity and encourage a person to approach.

Emotion, Motivation, and Attachment

Important emotions, too, appear early in life, without having to be learned. These so-called primary emotions include fear, anger, happiness, sadness, surprise, and disgust. Like tastes, emotions serve as signals to alert the conscious awareness about important stimuli, but they also serve as signals to others. The facial expressions that accompany primary emotions are performed consistently across cultures, even in children blind from birth. People instinctively understand the facial expressions signifying emotion and pay special attention when they see them.

Perhaps the most important emotion for survival and reproduction is the
attachment that develops between an infant and its mother.
Human infants are completely dependent on parental care and, even after weaning, require intensive investment and supervision. It is thus in the interest of both mother and child that a close bond form between them, to keep the child from wandering away and to keep the mother motivated to address the constant demands of her offspring. Infants can recognize their mother’s voice and smell soon after birth and, as soon as their eyes are able to focus, can recognize—and show preference for—her face. Once they are old enough to crawl, babies develop an intense desire to be within sight of their mother and, when temporarily separated, experience and communicate great distress. Mothers, reciprocally, develop an intense attachment to their children, and they, too, experience distress on separation.

Other social emotions also motivate people to repeat mutually beneficial interactions and to avoid people who might take advantage of them. Guilt and shame are cross-cultural universals that indicate disgust toward one’s own behavior and signal to others that one is unlikely to repeat the “rotten” behavior; allegiance and sympathy signal a willingness to help allies when in need; and vengeance and hatred warn those who have harmed someone that they endanger themselves if they approach again.

Personality, Sex Differences, and Social Relations

Predicting other people’s behavior is important, so any aspect of a person that is consistent and can help a person to predict accurately becomes worthy of attention. One source of predictability derives from consistent personality differences between the sexes. Boys and men around the world are, on average, more physically aggressive, more competitive, more impulsive, and more risk-prone than girls and women, who are, on average, more nurturant, more empathetic, more cooperative, and more harm-avoidant than boys and men. These differences have impacts on social behavior across the life span, influencing patterns of early childhood play, courtship, parenting, career choice, and participation in warfare, crime, and other high-risk activities.

In addition to sex differences, there are two major dimensions of personality that seem of particular importance: dominance/submissiveness and friendliness/hostility. As with tastes and emotions, one’s assessment of another person’s personality seems to highlight “good/safe” versus “bad/dangerous” and signals to approach or avoid, respectively. It seems that people attend to personality to determine who is likely to be a friend, to be trustworthy, and to be helpful, versus who is likely to hurt, to betray, and to take advantage.

In fact, it might have been the need to predict how other people might respond that led to human beings’ great intelligence. Like other social species, humans constantly monitor the statuses of those around them: who is fighting, who is having sex, who is popular, who is not. Compared with other animals, however, humans have taken this kind of mental tracking to a level that is quite complex: a man can think about what a friend might think if his sister told him that she heard that he knew that his girlfriend had heard a rumor that he was seeing someone else but that he had not told him . . . and so on. Such multilevel cogitation requires a great deal of long-term and short-term memory, as well as an extensive ability to manipulate concepts and scenarios.

Learning, Language, and Thinking

Given humans’ great intellectual capacity, evolutionary psychologists do not claim that all knowledge is inborn—it is obvious that humans acquire much information through learning. Nonetheless, evolutionary psychologists note that certain types of information are more easily learned than others.

Language, for example, is a kind of complex and abstract knowledge that comes as second nature to very young children. Across all cultures and languages, children progress through regular stages of language development, acquiring the ability to both understand and produce grammatical speech (or, in the case of deaf children, visual signs). At their peak, children actually acquire several new words an hour. Most adults, on the other hand, have to work extremely hard to acquire a second or third language, and it is exceedingly difficult to teach even the smartest computers and robots how to understand elementary forms of speech. Language is an example of a highly specialized kind of learning that is prewired into the human brain; it is acquired quickly during a critical period of brain development, and once achieved, it is never forgotten.

Similarly, humans readily develop mental stereotypes
that, once acquired, are difficult or impossible to disregard. Stereotypes are, basically, abstract generalizations that arise from the subconscious integration of personal and vicarious experience. Like tastes, emotions, and attention to personality, the automatic generation of stereotypes helps a person to respond quickly and appropriately to new stimuli without wasting precious time assessing each nuance of each situation encountered each new minute of every day.

Applied Evolutionary Psychology

Evolutionary psychologists do not claim that behavior that was once adaptive is necessarily still adaptive, nor that behavior that has evolved is unchangeable. For example, while stereotypes were designed to work to a person’s advantage, the experiences that now go into one’s mental computations include not only real experiences but also thousands of images from movies, newspapers, and television. As a result, stereotypes reflect not necessarily reality and true experience but rather the biases of the society at large, often amplified in the make-believe world of Hollywood. Taking an evolutionary approach to psychology suggests that although people will continue to create stereotypes, by changing or monitoring media coverage, increasing exposure to positive images, or broadcasting the voices of the unheard, the content of stereotypes could be changed. Like other approaches to psychology, evolutionary psychology has practical implications that can help people to understand—and improve—the human condition.

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