Sex at Dawn vs. sex today

There has been an undeniable shift in the conventional nuclear family over the last several decades, with increases in single parent, step-parent, grandparent and single-sex parent homes. A recent survey by the New York Times stated that as of 2009, women who gave birth under the age of 30 were for the first time less likely to be married than not. These trends, along with the rise in divorce rates seen over the last 40 years, support the relationship narrative put forward by Dr. Christopher Ryan and Dr. Cacilda Jetha in their book Sex at Dawn of long-term, semi-monogamous mates, rather than story-book life-long, monogamous marriages. Ryan and Jetha question the naturalness of our society's emphasis on exclusive and eternal pair-bonds. They cite the polyamorous relationship tendencies of our early ancestors and the sexual habits of our closest living relatives, free-loving bonobos and chimpanzees, as evidence that we were not always this way. They also list current hunter-gatherer societies who maintain looser definitions of sexual relations and expectations, and who have adjusted their property owning and child-rearing practices accordingly. Examples include the Curripaco tribe of Brazil, where a couple who hang their hammocks together are considered married (until one hangs her hammock elsewhere), or the Dagara of Burkina Faso, one of many societies in which every woman is called "mother" and every man "father" as questions of paternity are highly uncertain. Allocations of resources and affection are spread equally throughout these tribes, treating all as family and ensuring the well-being of every member of the community.

Ryan and Jetha's research is wide-ranging, in-depth and highly interesting, including evidence from anthropological, biological, philosophical and historical perspectives. Their arguments are compelling and for the most part well-thought-out, identifying flaws in the standard narrative of the evolution of sexual relations. The analysis on the anatomical differences in primates as evidence for different mating styles is particularly provocative and entertaining. For example, who would've thought that large external testicles were an indicator of sexual competition within species, preparing the males for battle in a "sperm war" in more free-wheeling and promiscuous females? As such male gorillas, the largest living primates, have the smallest relative penis and testicle size, as they enjoy a relatively stable role in the social hierarchy and a lack of sexual competitors. And who knew that female baboons vocalize during orgasm to attract attention from other future potential male suitors? Certainly puts Meg Ryan's famous deli scene in When Harry Met Sally into a new perspective!

However, one issue that I felt was glaringly under-addressed in their sexual manifesto was the question of jealousy. The authors acknowledge early on that this fundamental problem arises when contemplating the benefits and detriments of a more inherently promiscuous lifestyle, and promise to address the issue in full later in the book. However when the big moment arrives, they merely cite more tribes existing today who practice non-monogamous pair-bonding and communal child-rearing, and state that jealousy is not an issue in these societies. They further suggest that our deep feelings of jealousy are a learned result of our mating and marriage practices, stemming from the agricultural revolution and commoditization of women and children. There is no mention of the biological underpinnings of jealousy (thought to involve activation in the anterior cingulate cortex, the same area involved in feelings of emotional and physical pain, in case you were wondering), its potential evolutionary benefits, or its prevalence in modern society.

Now perhaps this is rather naive and un-empirical of me, but I find it difficult to swallow that the intense physiological pangs that nearly all of us have felt in the course of our romantic lives are a culturally created phenomenon. The visceral and automatic nature of these feelings would suggest that jealousy is a more organic emotion, rather than a learned response to a threat of ownership or security. Also if, as Ryan and Jetha claim, our naturally non-monogamous ways are the reason so many relationships fail, then why are we unable to evolve away from these underlying promiscuous tendencies but have developed these accompanying negative emotions in the meantime? Jealousy is a highly unpleasant experience that I would imagine few desire to feel, so why is it that we have created this emotion in ourselves that can be so painful?

For the most part, I found myself agreeing with Ryan and Jetha's hypothesis that humans were originally a more "promiscuous" species, rejecting life-long mates in favor of short-term or non-monogamous relationships. However my question to this new narrative they present is, so what? Are we to change our dating, mating and marriage habits today because our ancestors did it differently 2 million years ago? As our lives and cultures have evolved, to the extent that they are almost incomparable to the ones maintained by our ancestors, is it not natural that our sexual and romantic relationships would change as well? And even if these behaviors are more natural to humans than the practices we hold today, could we ever feasibly go back to that way of life, even if we wanted to?

(Thanks to Jesse Sleamaker for the recommendation for this book).

Dana Smith

PhD student in Experimental Psychology at the University of Cambridge