Came across a nice article in Psychology Today. It is by Alan S. Miller Ph.D., Satoshi Kanazawa Ph.D. They have a book coming out called Why Beautiful People Have More Daughters in late 2007.

We know that humans have been polygamous throughout most of history because men are taller than women.

Among primate and nonprimate species, the degree of polygyny highly correlates with the degree to which males of a species are larger than females. The more polygynous the species, the greater the size disparity between the sexes. Typically, human males are 10 percent taller and 20 percent heavier than females. This suggests that, throughout history, humans have been mildly polygynous.

Relative to monogamy, polygyny creates greater fitness variance (the distance between the “winners” and the “losers” in the reproductive game) among males than among females because it allows a few males to monopolize all the females in the group. The greater fitness variance among males creates greater pressure for men to compete with each other for mates. Only big and tall males can win mating opportunities. Among pair-bonding species like humans, in which males and females stay together to raise their children, females also prefer to mate with big and tall males because they can provide better physical protection against predators and other males.

Although I am a great fan of Evolutionary Biology, I am not sure if I always buy these arguments.

Also, I am not suggesting that alternative life style or swinging has anything to do with being polygamous. In fact it actually goes against the argument. In polygamous situations (in humans and in primates) there is a great deal of jealousy and and all the indicia of “possessiveness” present; in the swinging lifestyle that is not the case.

Swinging is more evolved, sophisticated and thoughtful response to hedonistic impulses. If it was as primal, one would see a lot more manifestation of it.