biology.monogamy

Mommy, where do monogamies come from?

 Monogamy is a rarity in the animal world, with biology favoring varying degrees of promiscuity as the reproductive tactic of choice. Yet, for this reason, the shaky, but constant appearance of the ideal of monogamy in human romantic relationships proves even more alluring. Sexuality has always played a pivotal role in many facets of human life, including: relationships and reproduction, spirituality and enlightenment, morality and social control, and oppression versus freedom, to name a few. Most societies around the world have high stakes in the understanding of monogamy, since most of them depend on moral constructs based on various degrees of sexual continence to facilitate thriving communities and individuals. 


There are piles of evidence that show that life-long monogamy is likely not a natural biological state for humans, but instead a complicated adaptation influenced by experience, culture, and perhaps even the pre-frontal cortex. Although monogamy is not the predominant mode of reproduction in the animal kingdom, most mammals form enduring mating relationships (mating bonds) with members of the other sex. An influential theory on why mammals form mating pairs was first introduced by Robert Trivers in 1972, and proposed an evolutionary theory that is still popular today. He proposed that because many mammals give birth to helpless, slow developing young, it is adaptive for males to stay with the female to increase the likelihood of successful development of the offspring, thereby passing on both parents’ genes. But mate bonding is a far cry from life-long sexual monogamy.


Daddy, are opportunists a kind of fish?
Female mammals must carry and nourish a fetus from their own bloodstream, undergo childbirth, and then provide additional metabolic investment in the form of milk. In contrast, males only have to produce a teaspoon-full of tiny sperm. This discrepancy in reproductive costs means that the best mating strategy for females is to be very selective in mating with males that have ample resources to raise young, physical prowess and dominance for protection, and hearty genes to be passed to young. Males, who will increase their genetic productivity by mating with as many females as will have them, will be non-discriminating. The imbalance of reproductive costs points to humans as being mildly polygynous, and certainly not naturally (that is to say, biologically inclined toward) monogamy. In the animal kingdom, there is ample evidence that most species, even those thought to be monogamous, engage in extra-pair copulations under certain circumstances. This phenomenon has even been noted in many types of birds, once thought to be the poster children of monogamous fidelity, as first cited by David Lack in 1972. One example is the osprey; also know as fish hawks, whose females will mate on the sly with other males in return for food when their mates don’t bring home salmon. Or barn swallows, whose females will have “affairs” with males who have deeply forked tails, which is a sexually desirable trait in male swallows, and thereby ensure long-term reproductive fitness through producing more attractive offspring.


 Mom, what is a biological tendency?
It seems that males invariably want more females than they can afford, or they want desirable females who are already mated to somebody else, and females want sex with males other than their mates, even at great personal risk, if the potential gain is sufficient. But, to say our biology favors a degree of polygyny is not to say that humans throughout history have been polygynous. In fact, only a few well-positioned males (that have enough resources and power to protect and raise many offspring, and fight off competition) could succeed at polygyny, and only a few attractive females (possessing the markers of youth and fertility) would be selected. Therefore, biologists have often called monogamy a strategy for the humble.  Monogamy is a mate-bonding pattern in which enduring bonds are formed between one male and one female. Monogamy is thought to have developed in those mammalian species in which each female could raise more fit young if she had undivided help.


Can I have a monogamy of my very own?
This brings me to my final consideration: Why do we strive for Monogamy in a culture where there are no environmental pressures that make it an arrangement of convenience? Why do we strive for monogamy when parenthood can be planned, is a choice, and not the sole purpose of life? Why do we strive for monogamy when we have a myriad biological tendencies that would like to see us copulate indiscriminately, in the case of males, and opportunistically, in the case of females? Barash and Lipton (whom I have paraphrased in this post) summarized it better than I ever could:

“ People are not condemned to be nothing more than genetic catapults, fleshy means by which DNA makes copies of itself. Harnessed to conscious human understanding and directed toward particular goals, understanding our biological selves can make a “miracle”- something of transcendence, harmony, and great beauty, nothing literally supernatural, but rather something memorable in which nature, with human help, surpasses it’s apparent limitations. To the technologically naive, an airplane is a miracle, at least in part, because a heavy, flying, man-made object is so profoundly “unnatural”. But airplanes work, and wonderfully well, in large part because they take gravity into account.” 

 In the case of society as it stands today, in the West at least, monogamy is most definitely like the airplane. It may not be natural, but it is how we travel further in our human potential than we have ever gone before. When we are not expending large amounts of energy constantly trying to mate, we can transcend our biological inclinations, and enter the realms of self-actualization, social cooperation, and enlightenment. To me, the mundane human experience of mere competition and survival that is offered by a purely biological outlook is nothing more that trying to fill an endless void. More, more, more; that is all your animal brain is concerned with. But conversely, in order for monogamy to fly, we must take biology into account.


Thanks! I will love it, and hug it, and feed it, and pet it...
 For some, monogamy is about mastery and control, for others about understanding and transcendence, and yet for others it is a moral endeavor. But lest we forget, it is also highly adaptive in a time of rampant sexually transmitted infections and overpopulation. If the mind is the next frontier, then our biological tendencies are the terrain we must understand to be able to delve more deeply into who we are, where we come from, and who we answer to. The most important aspect of humanity is that despite being an animal, we are so much more than that. Humans are the only animals that are not content with mere survival, and thus, using animal research to understand human sexuality will never be sufficient. Doing what comes naturally doesn’t always apply to us, since we find many "unnatural" things desirable and rewarding. Mastering a musical instrument, for example, takes time, energy, and effort, especially if it is to be done well.  If protracted monogamy is rare, so are good musicians. But both can be beautiful, as well as achievable. And monogamy doesn’t require talent, or perfect pitch. It requires knowledge, determination, and a belief that “A man’s reach should exceed his grasp”.

 References:

Barash D.P., Lipton, J.E. (2009). Strange Bedfellows: The Surprising Connection Between Sex, Evolution, and Monogamy. Bellevue Literary Press: New York