The Evolution of Human Genetics and Behavior | Freudian Psychology

We may think we are only a little lower than the angels, but we must not forget that we are a species of animal. Homo sapiens is our name. Our family tree spans the millions of years that life has been evolving on this planet. We are remarkable creatures. With bodily structures and psychological capacities shaped by evolutionary pressures over the millennia. Roughly speaking, bodily structures and behaviors that help an animal adjust to its environment tend to be the ones which persist. Under the pressures of evolution, behavior patterns have developed which are as much a part of our species nature as our structure and physiology. Understanding such species – specific behavior helps us to understand and explain behavior.

We shall examine our human species heritage, or the subject of evolution and behavior. But within the limits set by our species heritage, each of us (unless we have an identical twin) inherits from our parents a slightly different set of genes, or genetic constitution. People vary in their behavior partly because of differences in their genetics constitutions. So this aspect of our animal natures. These components play a large role in what we do – that is, in how we behave. Because of evolution, we have differently from other species of animals; because of genetics, we have differently from other people.

Evolution and Behavior.

Here we are, all 4 billion of us. How did our species, Homo sapiens, arrive on this planet? We do not know for sure, but we have a theory – the theory of evolution – that is now supported by an over. Whelming array of evidence. Although scientists continue to argue about certain details, the broad outlines of evolution are now so plain as to be unquestionable.

The Nature of Evolution.

Using the few facts that were available in the middle of the nineteenth century, the English naturalist Charles Darwin was able to make a convincing case for evolution in his book the origin of species, which was published in 1859. Darwin knew about the fossil record for many species of animals, and he knew that this record showed progressive development from species to related species. He had also observed – especially on his trip around the world which he recorded in another book, the voyage of the beagle – that animals develop structures which help them adapt to their habitats (environments). For instance, he observed that animals isolated on islands developed structures – and behaviors too – that enabled them to get the types of food available on those islands. He also observed that related species on nearby islands, where environmental conditions were slightly different, developed structures and behaviors appropriate to those environments. Darwin knew form his study of comparative embryology that higher animals pass through similar stages in their embryological developments, as if they had common ancestors. 

But much of the evidence we have today was missing in Darwin’s time. The fossils record of human beings was largely unknown then, and the evidence of biochemical similarities between related species was not known either. Darwin and his contemporaries did not fully appreciate the immensity of the time span available for evolution. But they made an inspired guess, backed by the evidence at their command that the various species of animals (human beings included) were the results of evolution – that is, of gradual changes from other, earlier forms of animal life. As the years have gone by, evidence supporting this idea of evolution has poured in. Today the fossil records are much more complete; we know something of the fossil record for Homo sapiens, and detailed changes in specialized structural features have been observed. Biochemical similarities of related species also molecular biology and an understanding of the cellular mechanisms of heredity, we now have a better idea of how the small changes necessary for evolution may have been passed on from generation to generation.