We must be so careful with language. It is such a powerful tool for describing, categorizing, and making inferences about the natural world. We sometimes forget that synonyms are contextually bound. The more precise our analysis, the more precise our language must be.
That being said, I fear that some of our discussions about human sexuality thus far have confused the term "natural" with the term "normal." Natural can be defined in many ways, but based upon its etymology, having some relationship with nature is a dominant theme. Normal is a statistical term, generally referring to a characteristic or behavior that is possessed or demonstrated by a large percentage of a population. A "large percentage" is often operationally defined as falling within one, two, or three standard deviations from the mean (around 68%, 95%, or 99.7% of the population, respectively).
So, is monogamy normal? Current scientific consensus says no, not really. When it comes to human beings, monogamous pairings have been standard practice in less than 20% of sampled societies. Although monogamy is the norm in contemporary western societies, this is a relatively new convention. Understanding monogamy from an evolutionary perspective can be difficult, since many inferences must be made based on available evidence. In addition, how researchers define monogamy runs the gamut, from descriptions of marital, social, sexual, serial, and even genetic monogamy.
Is monogamy natural? This is an extremely difficult question to answer, and any related discussion requires an understanding of what it means for something to be natural. I'm not sure how possible a consensus on this definition really is. One of the largest barriers to an agreement on how we define natural is an agreement on whether or not humans should be considered natural. Yes, we are biologically natural. We are made of the stuff of stars. We evolved the same way every other extant or extinct species that ever existed evolved--up to a point. Somewhere along the line, we developed cognitive capabilities that have been unsurpassed by any other documented creature. We use significantly more complex tools than any other ape in the wild. We wear clothing and build extravagant shelters to protect ourselves from extreme weather. We have language and art and culture and religion and tradition and ceremony. Are these practices natural? Are we subject to Darwinian natural selection? Or have we decommissioned evolution to some extent, subjecting ourselves to the artificial pressures of choosing mates based upon intellectual factors?
Looking again to our closest animal relatives, amongst primates in general, roughly 80% have been documented as predominantly polygamous. This figure is close to estimates of the existence of the practice amongst human hunter-gatherer societies. Only about 3-5% of known animal species have been documented to exhibit monogamous pair-bonding. And even in species where pairs are known to mate for life (many birds fall into this category), the majority of individuals "cheat." I wonder if this has anything to do with a recent study which posits that socially monogamous animals often settle for mates who are not very sexually attractive.
Regardless of labels, a central theme seems to be emerging in contemporary sexuality research: monogamy is not natural. This is not a moral opinion. This statement does not imply that monogamy is or is not somehow healthy or right for human culture or individual happiness. It also does not imply that monogamy is an unattainable goal for those striving to attain it. It simply means that monogamy does not seem to fit well within the natural landscape, especially that of our evolutionary predecessors.
What does this mean to you? What would you like to talk nerdy about tomorrow?