If this is all true, and it seems reasonable, it suggests some fascinating corollaries. Evolution may have selected for men who preferred to mate with robust, even chubby, women (remember all those obese Neolithic "Venus" fertility fetishes?) because it increased the probability of identifying a woman who could come to term successfully. But today, our intellectual understanding of the link between slimness and health has somehow overidden and modified a purely evolutionarily determined behavior. This is remarkable; it further suggests that our Darwinian-selected behavior can be subconsciously affected and modified by what we have learned and communicated culturally.

Both men and women are selected for the desire and ability to maximize the number and survivability of offspring. But there is one major physiological determinant: a woman can produce approximately one child a year, for about 20 years. A man can, in principle, produce a child a day, from puberty until the day he dies. This physiological difference is going to mean that from a purely evolutionary standpoint, a man and a woman's reproductive strategies, the means by which they find and keep mates, is going to be fundamentally different. Specifically, it is in a man's reproductive interest to have as many offspring by as many women as possible, and to let other men raise them. From the point of view of a woman's DNA, she really doesn't care who the father of her child is, as long as the man who protects her and her offspring is strong and has community standing and influence. She is interested in quality, not quantity, or even performance.

One would think that a harem system would be ideal for males, but humans don't seem to do this on a large scale, so it appears females have learned to enlist the loyalty of males by convincing them that it is in their best interest to ensure their offspring's survival by staying with one female. Culture helps with this by establishing ritual and custom to enforce monogamy through marriage, and when agriculture comes along, who gets to inherit the farm requires rigid social mechanisms to ensure families stay together and every one knows exactly who the mother AND father both are.

In every culture, marriage is a complex and binding ritual designed to intimidate and indoctrinate children barely out of adolescence that "this is really important and thou shalt not violate this agreement". The families and the tribe both collaborate to enforce this institution with multiple rules and regulations and elaborate legal and religious sanctions. Infidelity for males is tolerated, but not for females. But females still do so, in every culture. In order for such a coercive system to work, sex (which dominates male adolescent thought), and home-making and family building (which dominates female adolescent thought) is severely controlled so that adolescents are eager to marry as soon as possible, even if it's someone they don't even know, and that their parents have selected for them for reasons of their own.

Today, when we understand all this and have evolved technical and cultural ways to get around it, this system is breaking down. People want to control their own social and emotional lives, and their reproductive behavior, and now they have the knowlege to do so, and the freedom from cultural barriers which prevented them. Don't get me wrong, I certainly prefer modern Western sexual practices to tribal and medieval ones. But the question remains, is it really wise to abandon precipitously a system that has obviously served us well for thousands of years?

It's easy for us to talk like this, and make our own rules, but we are surrounded today by communities and subcultures whose family structures are breaking down with disastrous social results. Divorce, unwed mothers, child pregnancies, parental abandonments, abuse, even murder and other family dysfunctions are creating whole generations of children who are being raised in practically a feral state, without parental supervision or a stable family environment. Many of the social services and safety net provided by the family are now handled by social institutions, private enterprise, or by the state, and our economic system has little use for the non-productive, like children, non-working mothers, or the aged.

It is customary for traditionalists to blame the breakdown in religious control of society for this, but I feel it is the responsibility of technology and economic necessity, that is, the needs of our economic organization. Modern life is destroying families, and children without families will grow up to be monsters. The availability of contraception and abortions may help keep down the number of children born into destructive or non-existent families, but any species which voluntary reduces its reproductive capacity is playing along the edges of extinction.