Evolution and Psychology: A Mutual Relationship

From the lecture series: Understanding the Mysteries of Human Behavior

By Mark Leary, PhD, Duke University

Evolution and psychology go hand in hand. Discover how many baffling human behaviors and attitudes, such as a fear of heights, are rooted in evolutionary principles. 

Head silhouette with gear brain evolution concept.
(Image: Moonnoon/Shutterstock)

Mysteries of Human Behavior

When people think about the great mysteries of the world, they usually think about questions like whether there’s life on other planets, where the universe came from, or maybe who carved those huge stone heads on Easter Island. Those are indeed fascinating questions.

But we are surrounded every day by mysteries that are often just as interesting, mysteries that involve what, on the surface, appear to be rather ordinary human behaviors.

What makes people happy? Think about that for a moment. You may know—or think you know—what makes you happy. But do you? If you do know, why do you still do things that make yourself unhappy?

This is a transcript from the video series Understanding the Mysteries of Human Behavior. Watch it now, on Wondrium.

Or have you ever thought about why people overreact and make giant mountains out of tiny molehills, or why different individuals from the same family often have such different personalities?

Why do some marriages and other close relationships work out, whereas other ones end in disaster? We might make a fortune if we figured out the answer to that one!

Let’s explore the latest theories and research from psychology and other behavioral sciences as we try to understand a variety of rather ordinary—but often puzzling—aspects of human behavior.

Origins of Psychology

People have been interested in questions about human behavior since the beginnings of recorded history. If we look back at the ancient philosophers—such as Plato and Aristotle—much of what they philosophized about involved human behavior.

Later, philosophers were joined by theologians who also got involved in trying to understand why people do what they do, often basing their speculations on religious doctrine.

Many of the ideas that philosophers and theologians had over the years were right on target. These were smart people with a lot of insight into human nature. But many of their explanations also turned out to be completely wrong.

We shouldn’t fault them for having drawn wrong conclusions—even modern researchers sometimes make mistakes. But the difference between then and now is that, before the emergence of scientific methods, those early thinkers couldn’t test their ideas the way that behavioral scientists can today.

Anyone was free to speculate about these questions, but there wasn’t a way to determine which ideas were right and which ideas were wrong.

Then, during the latter part of the 1800s, scholars began to realize that we could answer questions about behavior using the same kinds of scientific thinking that were already successful in the sciences, such as biology, chemistry, and physics.

The phenomena being studied were different, but the same kind of scientific reasoning and research designs could be used to study emotion, motivation, memory, personality, intelligence, and other aspects of human behavior.

Today, more than 120 years later, the work of a few creative scientists has blossomed into a large enterprise, involving hundreds of thousands of researchers around the world who study behavior and psychological processes.

Learn more about puzzling aspects of human behavior

The Scopes Monkey Trial

You have probably heard of the famous Scopes Monkey Trial that occurred in 1925. John Scopes was a public school teacher placed on trial for violating a Tennessee law that banned the teaching of evolution in public schools.

The Scopes trial captured the country’s attention—much like the trials of O. J. Simpson and Casey Anthony grabbed the headlines in our lifetime. In part, the trial intrigued people because it involved two well-known and flamboyant lawyers—Clarence Darrow and William Jennings Bryan.

But people were also captivated by the fact that the trial involved several controversial and emotionally charged issues: The debate between science and religion regarding where human beings came from, separation of church and state, academic freedom, the infallibility of the Bible, and whether Darwin’s theory of evolution was an established scientific fact.

One issue at the center of the courtroom drama that summer involved the question of how human beings differ from other animals. The prosecution strenuously objected to Darwin’s view that human beings evolved according to the same biological processes as every other animal.

Portrait of Charles Darwin and evolution of man.
Charles Darwin’s theory of evolution was that human beings evolved according to the same biological processes as every other animal. (Image: UncleLeo/Vectorstock)

Although biological research supports the idea that human beings evolved through natural selection, we can understand why many people, then and now, have a difficult time viewing human beings as just another species. We certainly resemble other animals in certain respects, but in other ways, we are so dramatically different from all other animals that it’s easy to see why many people have trouble believing that we were cut from the same cloth.

We create great art and great music, we build cities, establish governments, fly airplanes, design computers, and watch reality television shows—and we have created an environment for ourselves that’s totally unlike anything in nature.

Just look around you. All of the rest of the animal kingdom, at least those in the wild, is still living just as they always have.

But we have created a very different environment for ourselves from the one in which we evolved. Human beings are unusual animals to be sure, and many of the answers to puzzling aspects of human behavior lie in understanding some basic things about human beings.

How are we similar to and different from other animals? And, how are the things that influence our behaviors and emotions similar to and different from the things that affect other animals?

To answer that question, let’s look at three broad themes that will follow us through our investigation into the mysteries of human behavior: evolution, self-awareness, and culture.

Learn more about five key areas of our behavior in which evolution plays a critical role

The Evolutionary Function of Fear

Like all life on Earth, human beings have evolved through a process of natural selection that turned us into the kind of animal that we are.

Evolution is important in understanding certain mysteries of human behavior because, in some cases, a behavior that is difficult to understand today makes sense when we consider the possibility that the puzzling behavior evolved to deal with a particular problem that our ancestors faced during the distant evolutionary past.

For example, many people experience a fear of heights when they look out of a tall building, for example. They know that they are perfectly safe, they will not fall, and that they are in no danger.

But they still feel uneasy, if not sometimes highly anxious. It seems irrational, and it is.

But for millions of years, when people looked down from a very high place, they weren’t in a building. They were probably up in a tree or at the edge of a cliff, and they had every reason to be nervous and careful.

In fact, those individuals who were not nervous were often careless and didn’t survive. We are the descendants of people who were uneasy and cautious in high places.

It makes no sense in a tall building, but skyscrapers did have not existed until the last 150 years or so. Human evolution occurred over millions of years, and today, we sometimes see vestiges of our old responses from back when we were hunters and gatherers.

Learn more about heritability at work in everyday traits ranging from extraversion and neuroticism to smoking, divorce, and even political beliefs

This idea that some of human being’s puzzling behaviors are rooted in our evolutionary past continues to crop up again and again.

Common Questions About Evolutionary Psychology

Q: Who is the creator of evolutionary psychology?

Evolutionary psychology is generally thought to have begun with Charles Darwin’s theories on natural selection.

Q: How exactly does Darwin’s theory of natural selection affect evolutionary psychology?

Evolutionary psychology stems from the idea that the natural selection of traits results in the most successful traits being passed on through reproduction.

Q: What exactly is evolutionary psychology?

Evolutionary psychology is the study of behavioral psychology and emotions that are passed down from our ancestors’ successful navigation of human existence.

Q: What are the primary principles of natural selection?

There are four primary principles to natural selection: 1) Variation—the variety of heritable differences in all populations; 2) Overproduction—populations fight for resources; 3) Adaptation—the ability to successfully reproduce; 4) Descent with Modification—genetic transfer of successful traits.

This article was updated on December 7, 2020

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