Evolutionary Psychology

I'll try to make this as painless as possible, but you really need to know a bit about it in order to make the best of your life.

For the last twenty-five or thirty years, there has been a new field of study at universities called Evolutionary Psychology. It is based on this notion: just as all of our other organs evolved through natural selection, so did our brains, including our behavioral tendencies.

It works like this: if some people have genes that incline them to a particular behavior, and that behavior is helpful to their survival and reproduction, then those genes, and that behavior, will tend to spread in the population, and if it is a powerful improver, then pretty soon everyone will have it. To take some basic examples (which we share with most of the animal kingdom): if you (or your child), are hungry, or thirsty, you will not focus on anything besides getting food or water--unless there should be a threat to your life such as a predator. And if a person is not inclined to love and care for their children, then that person's genes are not likely to be perpetuated.

That's pretty much it. Except for a couple of additional refinements.

First, nature vs. nurture. The inborn behavioral tendencies that we have are not solely responsible for our behavior--the environment we live in is also a major factor. Our life experiences also shape us, particularly our families, but also other experiences, with peers and others. To take an extreme example, think of the child soldiers in some African (and other) countries. Their behavioral tendencies have been badly distorted by their environment.

Second: the "ancestral environment" or "the environment of evolution". This is a critical concept in Ev Psych, based on this idea: evolution does not (usually) work instantly, in a generation or two: especially with something as subtle as a behavioral tendency.  It usually takes hundreds or  thousands of generations to make a big shift in the behavior of "most people". So if you assume that a human generation (the average time between a peron's birth and their child's birth) is twenty years, that's five generations per century, which is fifty generations per thousand years. Civilization (living in cities) started about ten thousand years ago, and we split off from chimpanzees about five million years ago, so for the great majority of our evolution, we were living in hunter-gatherer bands of between ten and a hundred people. So the behaviors that benefited us in those circumstances constitute most of our "inborn behavioral tendencies".