By the end of the 20th Century, scientific research on animal behavior and brain chemistry were providing strong confirmation of the troubling observation many of us had already made through personal experience - that life long monogamy is not natural for humans, nor for most other animals.

As David Barash and Judith Lipton discuss in their book The Myth of Monogamy which was published in 2001, the advent of DNA testing to determine paternity was a major breakthrough in the study of animal mating patterns. Many species previously thought to be monogamous have since been found to be socially monogamous at best. That is, they may mate with a single individual, setting up housekeeping, co-parenting, and sharing resources. But DNA testing along with behavior observation reveals that in many species both males and females have “secret affairs” often with other partnered individuals.

Barash and Lipton’s analysis of the proven absence of sexual exclusivity, even in most socially monogamous species, revolves around genetic programming. That is, both males and females will behave in ways that increase the likelihood of reproducing, and in the survival and successful mating of their offspring. This includes their parenting behaviors, and other social behavior, as well as sexual habits. Barash and Lipton also mention ecological considerations, what deep ecologists call the “carrying capacity of the land” as secondary influences on reproductive behaviors and we’ll come back to this interesting factor in a later chapter.

The viewpoint which we could call DNA driven sexual behavior, is by no means new. But twentieth century male sociobiologists frequently had blinders on when it came to the reproductive advantages accruing to females when mating with multiple males. It took women scientists whose observations and interpretations often differed markedly from those made by men, to give us a more accurate picture. Barash and Lipton, who are a male-female team, provide a more unbiased perspective, putting to rest the outdated notion that females are naturally sexually exclusive. Instead, their data reveals that females, like males, are largely motivated by reproductive advantage and access to resources.

In addition, they pose the fascinating question of why monogamy exists at all, in any animals including humans, and even go so far as to compare the reproductive advantages of monogamy, polygyny (one male, many females) and polyandry (one female, many males).

The animal behavior studies are illuminating. But while genetic programming dictates much more of our behavior than most of us like to admit, there are at least two serious limitations to animal research – and Barash and Lipton’s analysis -- for understanding human sexual behavior.

The first is that there are basically no precedents either in the animal world or in so-called primitive cultures for mating or family groups that include more than one member of both genders. For example, the concept of two males and two females bonding to reproduce and raise young, is conspicuously absent from the literature. And while polyamory does not have to include multiple partners of both genders, it certain can.

The reason for this, undoubtedly, is that while conflict between same gender individuals competing to fertilize an egg, control territory, or obtain food and childcare is generally present, when one male or female establishes dominance, they are able to assert themselves over the others. But imagine what would happen if the alpha male or patriarch is not only ruling his harem, he is also constantly competing with another male who he can’t simply defeat and drive away, but one with whom he needs to cooperate on an ongoing basis. A male who willingly submits to another becomes unattractive to females programmed to go for male with the best genes. Similarly, an alpha female will generally not allow another female into her “home,” and a non-alpha female will not succeed in preserving her freedom to have multiple mates in the face of inevitable resistance from males who want the genetic advantage of fertilizing all her eggs.

Genetic programming, so far as it’s understood, is “selfish.” It’s not interested in the good of the species, or the happiness of others, or social justice, but ruled by Darwin’s infamous survival of the fittest dictum. Competition and the struggle for dominance, whether at the level of determining which sperm cells will fertilize an egg, or which male has access to a particular female, or whether the male or the female is calling the shots, has been the basis for most interpersonal interactions throughout our known history. Polyamory, on the other hand, involves a conscious decision to act altruistically – that is, to put the well being of one’s partner(s) on an equal par with one’s own.