The Moral Animal by Robert Wright, 1994.
The theory of evolution states that genes which increase the ability of an individual to have successful offspring will tend to spread through a population. An organism with beneficial genes survives, breeds, and in turn has young who breed, replicating the genes. Deft hands and sharp eyes are a product of natural selection, and so too is the brain.
Our emotions are a direct result of evolution; they are mechanisms which help us survive and prosper. This realization has led to new insights in psychology. Robert Wright explains a number of human impulses from a Darwinian view in The Moral Animal by looking at examples from sociology, anthropology, the animal kingdom, and Charles Darwin's life. I've summarized below a few of the points he discusses in the book.
Ancestral Environment
Most of our evolution took place in our ancestral environment (also called our environment of evolutionary adaptation). In other words, we've changed very little since becoming "civilized" - the bulk of our evolution took place during when we were simple hunter-gatherer clans in prehistoric times. Many of our emotions, and secondarily many of our social conventions, are a result of evolution during this primitive period.
Male Parental Investment
As a species, our most outstanding characteristic is our large brains. At birth, that fabulous brain is empty, and worse still it makes the baby's head especially large in proportion to its body. Because of this, a baby was helpless and defenceless to predators for years after birth in the ancestral environment. As compensation for this we've evolved what behavioral scientists call high male parental investment (MPI). In other words, human males support and care for their young to a far greater degree than males of most species.
Men and Women
We've evolved to want what will spread our genes most efficiently. Because of different reproductive roles the two genders have different agendas, and different desires in a possible mate.
For a man, the best strategy from an evolutionary standpoint is to have sex with as many women as possible, indiscriminately. Sex is nearly a no-cost proposition for the man, and each new woman means a new possible child. Of course, without MPI the children may not prosper or even survive, so a sound tactic is to find an especially good female and form a permanent or semi-permanent relationship with her, putting the bulk of his resources into her children.
Because of this strategy men tend to favor beauty and youth - a younger woman has more childbearing years left.
Women face an entirely different proposition. Each woman may only have a very limited number of children, and each child means nine months of pregnancy as well as the years of caring for a helpless child after birth. If a woman wants to do well she must be far more discriminate because the consequences for sex are far higher for her (especially so in the ancestral environment).
For a woman, wealth is far more important than youth or beauty. Not only is a man fertile longer, but older men tend to be wealthier, and wealth and status can help alleviate the burden of child rearing.
Marriage
Because we are a high MPI species it behooves us to pair up in monogamous relationships. At the core of a monogamous relationship is the promise of fidelity.
Why is sexual fidelity so important? For a man, if his wife has sex with another man he may end up spending resources for years to come in supporting someone else's child. From the standpoint of his genes, this is a terrible thing. From a woman's view, if her husband has sex with another woman he may father other children and therefore have less resources to spend on her's.
Traditionally an exchange of resources accompanies a marriage. In medieval times a dowry or bride price, today an expensive engagement ring for the woman. The ring is a sign of good faith and assures the woman that should her husband break the bargain, she has something of value to sell to help support her children.
Love
Love is the emotion that mother nature provided to keep us on the right track. Romantic love is there to keep us together in monogamous relationships long enough to raise children. Parental love assures sacrifice by the parent so that the child will receive all that he needs.
Grief
Much like our sense of pain, grief is there to help us avoid that which is harmful to us. When asked to imagine the loss of a child, parents report that the grief felt varies with the age of the child. Potential grief increases steadily from birth to adolescence which then gradually decreases through the rest of the child's life. Parents feel greatest grief at the loss of an adolescent because it's the age when much has been invested in the child yet all of their reproductive years still remain.
Friendship
The desire for friendship arose out of the realization that reciprocal altruism is not a zero-sum game. In other words, sharing (whether it be information, food, danger...) is usually beneficial for all involved. Today you may have more meat than you can eat - sharing is a small sacrifice for you, but a large gain for me if I'm starving. Next week I may be the one with food, and you in need. Friendship allows us to cultivate such beneficial relationships.
Justice
Unconsciously we track our relationships in a kind of mental balance sheet so that we may know who is a worthy friend and who is not. Should a friend be a bad one with too many marks in the debit column, anger and a sense of injustice are the result, a sign that resources should not be wasted on this unworthy friend in the future.
Evolutionary Ethics
These and many other things are gifts of natural selection. Knowledge of their origins can teach us something about ourselves. It cannot, however, tell us anything about what is right. The belief that because something appears in nature means that it is right is referred to as the "naturalistic fallacy" and is illogical. It appears in the guise of phrases such as "might makes right" and has been used by countless dictators to justify their social policies.
Evolutionary psychology tells us why we are the way we are, not how we should be.
Conclusion
The Moral Animal opened my eyes regarding human nature. It sounds dramatic but is true. Wright has a pleasant writing style and the book was an easy read, with just a few slow parts when he uses biographical examples from Darwin's life. Pick up the book and fill in the gaps that my brief examples left, you won't regret it.
