Four Core Principles of Evolutionary Psychology - What Is Evolutionary Psychology?

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Four Core Principles of Evolutionary Psychology
What Is Evolutionary Psychology?

Evolutionary psychology, at the most fundamental level, is the study of human nature. Human nature consists of what evolutionary psychologists call evolved psychological mechanisms or psychological adaptations (which are roughly synonymous with each other). Evolved psychological mechanisms provide solutions to adaptive problems (problems of survival and reproduction). Through a long process of natural and sexual selection, evolution has equipped humans with the ability to solve important problems, by allowing those who could solve the problems to live longer and reproduce more successfully and by eliminating those who couldn’t. Those who had these innate solutions in their brain enjoyed distinct advantages over those who didn’t, and lived longer and produced more children who survived. And their children inherited their parents’ genetic tendency to solve these problems, and, in turn, lived longer and had more children themselves.

Over time there were more and more people who had these solutions in their brains and fewer and fewer people who didn’t, until these innate solutions to adaptive problems became universal, characterizing all normally developing members of the human species. Human nature is therefore universal or species-typical (typical or characteristic of all members of a species). Some evolved psychological mechanisms are specific to only men or only women; others are shared by both men and women.

The important point to remember is that the psychological adaptations produce the correct solutions to the adaptive problems only in the context of the ancestral environment. Evolved psychological mechanisms are designed for and adapted to the conditions of the ancestral environment, not necessarily to those of the current environment. Evolution cannot anticipate or foresee the future, so its products—evolved psychological mechanisms—are not necessarily adapted to the conditions that emerged after they were designed. To the extent that our current environment is radically different from the ancestral environment, where our ancestors lived on the African savanna as hunter-gatherers in a small band of about 150 related individuals,2 then the execution of the evolved psychological mechanisms does not necessarily produce the correct solutions to the adaptive problems at hand. In fact, as you will see below, it often produces the wrong solutions.

Our ancestors were, and had been for more than a million years, hunter-gatherers, first in Africa, then elsewhere on earth. Their hunter-gatherer lifestyle came to an (evolutionarily speaking) abrupt end around 10,000 years ago, when agriculture was invented. The invention of agriculture at around 8,000 BC is probably the single most important event in human history. Agriculture necessitated sedentary life; our ancestors, for the first time, ceased to be nomadic and stayed put in one place. That led to permanent settlements, villages, towns, cities, houses, roads, horse carriages, bridges, buildings, governments, democracy, automobiles, airplanes, computers, and iPods. The iPods would not have been possible without agriculture and everything else it led to.

Four Core Principles of Evolutionary Psychology

Evolutionary psychology, in its intellectual origin, is the application of evolutionary biology to human cognition and behavior. Ever since Darwin, evolutionary biologists and zoologists had known that principles of evolutionary biology applied to all species in nature, except for humans. In 1992, a group of psychologists and anthropologists, following the courageous lead of E. O. Wilson,3 simply asked “Why not?”4 Why are humans exceptions to the rule of nature? Why not apply the same principles of evolutionary biology to humans as well? And thus evolutionary psychology was born, merely 20 years ago. It's a very new science. But it has made tremendous progress in its very short history.

As an application of evolutionary biology to human cognition and behavior, evolutionary psychology is based on four core principles.

1. People Are Animals5

The first and most fundamental principle of evolutionary psychology is that there is nothing special about humans. This realization, that humans are not exceptions to nature but part of it, initially led the original evolutionary psychologists to apply the laws of evolution by natural and sexual selection to humans. It turns out that humans are not exceptions to nature at all, but just another animal species.

Scientists once believed that humans possessed many traits that were strictly unique to humans and that no other species had, such as culture, language, tool use, consciousness, morality, sympathy, compassion, romantic love, homosexuality, murder, and rape. This turns out to be false. Recent scientific research has shown that there is at least one other species that shares any trait that humans have.[6] To the best of my knowledge, there are no traits that only humans have.

This, however, does not mean that humans are not unique. To quote the great sociobiologist Pierre L. van den Berghe, “Certainly we are unique, but we are not unique in being unique. Every species is unique and evolved its uniqueness in adaptation to its environment.”7 The fact that humans are unique means that no other species have the exact constellation of traits and characteristics that humans have. If chimpanzees were exactly the same as humans in every possible way, then they would not be a separate species from humans; they would be humans. Humans are a separate species because no other species is exactly like humans.

But this is true of every species in nature: dogs, cats, giraffes, cockroaches. No other species is exactly like cockroaches. Humans as a species are just as unique and special as cockroaches, no more, no less. Every species in nature is equally unique.

The unavoidable conclusion from evolutionary biology is that there is nothing special about humans as a species, and we are just another ape species in nature. As such, all laws of biology hold for humans as they do for all other species. And this includes the law of evolution by natural and sexual selection, which states that the ultimate goal of all living organisms is reproductive success. All living organisms in nature are designed by evolution to reproduce and make as many copies of their genes as possible.

2. There Is Nothing Special about the Human Brain

For evolutionary psychologists, the brain is just another body part, like the hand or the pancreas. Just as millions of years of evolution have gradually shaped the hand or the pancreas to perform certain functions, so has evolution shaped the human brain to perform its function, which is to solve adaptive problems to help humans survive and reproduce successfully. Evolutionary psychologists apply the same laws of evolution to the human brain as they do to any other part of the human body.

Social scientists tend to believe that evolution stops at the neck.8 They believe that, while evolution has shaped the structure and function of every other human body part, the human brain has been immune to evolutionary history. In sharp contrast, evolutionary psychologists contend that the human brain is not an exception to the influences of evolutionary forces on the human body. Evolution does not stop at the neck; it goes all the way up.

3. Human Nature Is Innate

Just as dogs are born with innate dog nature, and cats are born with innate cat nature, humans are born with innate human nature. This follows from Principle 1 above. What is true of dogs and cats must also be true of humans. Socialization and learning are very important for humans, but humans are born with the innate capacity for cultural learning. Pierre van den Berghe continues the quote above by saying, “Culture is the uniquely human way of adapting, but culture, too, evolved biologically.” Culture and learning are part of the evolutionary design for humans. Socialization merely reiterates and reinforces what is already in our brain (like the sense of right and wrong, which we share with other species9).

This principle of evolutionary psychology is in clear contrast to the blank slate (“tabula rasa”) assumption held by most social scientists.10 They contend that, because evolution stops at the neck, humans are born with a mind like a blank slate, on which cultural socialization must and can write anything whatsoever. Evolutionary psychologists strongly reject the tabula rasa assumption of the social sciences. In the memorable words of William D. Hamilton, who is universally regarded as the greatest Darwinian since Darwin, “The tabula of human nature was never rasa and it is now being read.”11 Evolutionary psychology is devoted to reading the tabula of human nature.

4. Human Behavior Is the Product of Both Innate Human Nature and the Environment

There are a few genetic diseases, such as Huntington's disease, that are 100% determined by genes. If someone carries the affected gene, they will develop the disease no matter what their experiences or environment.12 An individual's eye color or blood type is also 100% determined by genes. So these (and a very few other) traits are entirely genetically determined. Otherwise, there are no human traits that are 100% determined by genes. Nor are there any serious scientists who think there are complex human behaviors that are entirely determined by genes. Contrary to what the critics of evolutionary psychology often claim, there are no genetic determinists in science.

Genes for most traits seldom express themselves in a vacuum. Their expressions—how the genes translate into behavior—often depend on and are guided by the environment. The same genes can express themselves differently depending on the context. In this sense, both innate human nature, which the genes program, and the environment in which humans grow up and live, are equally important determinants of behavior.

Many social scientists believe that human behavior is 100% determined by the environment, and genes and biology have absolutely no role to play in it.13 In sharp contrast, evolutionary psychologists do not believe that human behavior is 100% determined by either genes or environment alone. However, evolutionary psychologists tend to emphasize the biological and genetic factors in their research, because they are fighting the supremacy of environmentalism (the belief that the environment determines human behavior 100%) both in the social sciences and among the general public. Nobody is surprised to learn that the environment influences behavior; that is not news. But people are often surprised by the extent to which genes influence behavior. That is news.