Nature and Social Behavior: THE SOCIAL BRAIN

Trees don’t need brains, and solitary creatures can get by with relatively simple ones. Social animals, however, require brains with additional, flexible capabilities.

The evolutionary anthropologist Robin Dunbar (1993, 1996) compared the brain sizes of many different species to see what behavioral differences went with bigger brains. (Brain size is always adjusted for body weight, because bigger animals generally have bigger brains. For example, human men have bigger brains than women, but that’s mainly because men are bigger all over.) Did big-brained species eat better foods, or more complicated foods such as fruit (which ripens and turns rotten rapidly)? Did they roam over larger territories, so that they needed a bigger brain to maintain a more complex mental map? No. What Dunbar found was that bigger brains were mainly linked to having larger and more complex social groups. Small-brained animals tend to live alone or in small, simple groups, whereas bigger-brained, presumably smarter animals have more relationships with each other and more complicated groups (such as those with dominance hierarchies and competing allies).

Th is conclusion is highly important. The human brain did not evolve because it helped us outsmart lions and tigers and bears, or build better shelters, or invent calculus. It evolved mainly in order to enable human beings to have rich, complex social lives. Th e brain is not for understanding the physical world around us, so much as it is for understanding each other. It is not so much a calculating brain or a problem-solving brain as it is a social brain.

Nature and Social Behavior: SOCIAL ANIMALS

Psychologists study people. Many psychologists have studied other animals, especially rats. But psychologists have never shown much interest in studying trees. Why not?

Trees, like people and all other living creatures, need to get certain things (e.g., water, nutrients) from the world around them. What is inside them is there to enable them to get what they need. The inside parts of trees enable them to draw water from the soil, chemicals from sunlight, and so forth. Trees, however, do not move around in search of food or to escape from predators. They take what comes to them where they are. Facing few decisions and being therefore essentially indifferent to other trees, they do not have much psychology. They don’t have much in the way of thoughts, feelings, or behavior, because they don’t need these things to survive and reproduce. (That’s why psychologists don’t find them interesting.)

Contrast this with animals who also live as loners. They have to find food, possibly kill it, and eat it. They need more food and produce more waste than trees do. They need to sleep and so must find safe places to do so. Reproduction is more complicated than it is for trees, so they may need to perform a particular set of behaviors in order to reproduce. Like trees, they need to interact with their world, but doing so is more complicated for animals, so what is inside them has to be up to the task. Psychologists start to get interested in these processes.

Nature and Social Behavior: SURVIVAL

Survival is not hard to understand. It means living longer. Darwin’s contemporary Herbert Spencer coined the phrase “survival of the fittest” to describe natural selection.

Animals compete against each other to survive, as in who can get the best food or who can best escape being eaten by larger animals. In a group of zebras, for example, the ones who run the slowest are most likely to be eaten by lions, so the ones born to be fast are more likely to live long enough to pass along their genes.

Survival depends in part on the circumstances in your environment. Consider the coloring of fish. Almost all fish have a relatively light colored belly and a relatively dark colored top or back. Why? Th at coloring is adapted for survival in the water. Most fish live until a bigger fish eats them, making the ability to hide from bigger fish an important trait for survival. Some big fish swim near the surface and look downward for food. Th e lower (deeper) you go in the water, the darker it gets. When a big fish looks downward, therefore, it can’t see dark-colored fish very well, so fish who are dark on the top side are harder to see (and therefore safer). Meanwhile, some big fish lurk in the depths and look upward for their food. Looking upward is looking into the light, so the best way for a fi sh to blend in is to have a light coloring on its underside. Over millions of years, the fish who were dark on top and light on the bottom survived longest because they were the hardest for the bigger fish to see, so they were less likely to be eaten and, therefore, more likely to make more baby fish with the same coloring. As a result of this selection process, most fish have this coloring today.

Nature and Social Behavior: EVOLUTION, AND DOING WHAT’S NATURAL

Over the past two decades, many social psychologists have begun looking to the theory of evolution to help explain social behavior.

The theory of evolution, proposed by the British biologist Charles Darwin in the 1800s, focuses on how change occurs in nature. Over thousands of years, a type of plant or animal may evolve into a somewhat different kind of creature. Human beings and the great apes evolved from a common ancestor.

Human beings may be different from all other animals, but we are animals nonetheless. As such, we have many of the same wants, needs, and problems that most other animals have. We need food and water on a regular basis, preferably a couple of times every day. We need sleep. We need shelter and warmth. We need air. We suffer illnesses and injuries and must find ways to recover from them. Our interactions with others are sometimes characterized by sexual desire, competition, aggressive impulses, family ties, or friendly companionship. Sometimes we say that certain people are “acting like animals,” but this is not surprising, because we are all animals. Th at phrase merely expresses the point that people can sometimes rise above their animal nature, but the animal parts are there inside all of us.

Nature and Social Behavior: NATURE DEFINED

Behavior geneticists seek to understand behavior as the result of genes and show that people are born with tendencies to feel and act in certain ways

Nature is the physical world around us, including its laws and processes. It includes the entire world that would be there even if no human beings existed. Nature includes trees and grass, bugs and elephants, gravity, the weather, hunger and thirst, birth and death, atoms and molecules, and all the laws of physics and chemistry. Nature made people too. (People who believe that the original humans were created by a divine power still recognize that the natural processes of reproduction and childbirth create today’s people.)

Those who use nature to explain human behavior invoke the sorts of processes that natural sciences have shown. For example, neuroscientists look for explanations in terms of what happens inside the brain (chemical reactions, electrical activity). Behavior geneticists seek to understand behavior as the result of genes and show that people are born with tendencies to feel and act in certain ways. Above all,however, the advocates of nature in psychology turn to evolutionary theory to understand behavior patterns. Th e next section provides an introduction to this style of thinking.

Nature and Social Behavior: EXPLAINING THE PSYCHE

One approach to understanding how people think, feel, and act is to try to understand what the human psyche is designed for. (Th e psyche is a broader term for mind, encompassing emotions, desires, perceptions, and indeed all psychological processes.) To understand something, you have to know what it was designed to do.

Imagine someone who has grown up on a deserted island and has never met another human being or seen any man-made items. Th en one day a box washes ashore containing an electric can opener. How would the person figure out what the can opener does? Having grown up on a deserted island, the person knows nothing about cans or electricity. Th is hypothetical person might take it apart, analyze it, observe its parts, and see what some of their properties are, but it would be almost impossible for this person to understand it properly.

Understanding the human psyche is somewhat like that. We want to understand and explain how it works. To do that, it is useful to know what the psyche/human mind is designed for. Hence we turn to nature and culture, because those are what made the psyche the way it is. If the psyche was designed for something in particular, then nature and culture designed it for that purpose. Accordingly, if we can learn what the purpose is, then we can understand people much better.