Is the Human Species Sexually Omnivorous?

I wrote a new post for the “Evolution Institute” website. I had wrapped up the Humans are (Blank)-ogamous series, but a friend asked if I would write something for the site. So, this is what I came up with. It has a few snippets from the series, but the majority of it is new. I’m always tentative after writing, not knowing if it’s any good or not. Now that I’ve re-read it a few more times, I think it’s not too shabby. Anyway…

Is the Human Species Sexually Omnivorous?

Wrapping up the (Blank)-ogamous Series


“We have both a moral and ethical responsibility to protect all children and adolescents in our community. We cannot withhold information from children, adolescents, or adults, live in silence about this taboo subject and expect everything to turn out all right. We have tried ignorance and it does not work.”

– Jocelyn Elders, former Surgeon General, writing about human sexuality (2010: 249)


A few years ago, I began the “Humans are (Blank)-ogamous” series. I originally intended it to be only a few posts that would explore the roles that evolution and culture play in human sexual behavior. The inspiration for it was that several theorists over time had proposed that humans had evolved to be a number of things – monogamous, polygynous, serially monogamous, promiscuous, etc. I wondered how people could look at the same species and reach such different conclusions. Perhaps if I could read enough I might be able to find “the answer.”

From there, the series grew, blossoming into 20+ posts, citing over 200+ references (yes, I counted). I probably could have gotten at least a Master’s Thesis out of this. Anyway, those posts easily have been among the most read things on this site. That’s not because they are particularly brilliant. Rather, I think it’s because people are hungry for credible information and – despite how important the topic of human sexuality is – that can be hard to come by. Having those three magic letters “Ph.D.” after one’s name can help with internet search engine results, but a Ph.D. is no guarantee of being right. Far from it. All that means is that I went to school for a long time. I’m still in school, actually, so there’s always more to learn…

The series has been pretty well received by a number of people I admire, which feels pretty good I have to admit (I’m tempted to name drop here, but I’ll resist the urge). They’ve been shared on social media, and some posts were even included on different university syllabi. In fact, I taught my own class on the subject last semester, and I think it went very well. When I re-read some of the earlier posts, there isn’t too much that I regret, (which is a good sign – sometimes when I reading my old stuff I sound like Sideshow Bob stepping on a rake).  

With all that said, I think I think I’d like to wrap this up by taking the utilitarian approach. If I’m confident about anything that I wrote, and willing to put my money where my mouth is, then what would I emphasize to my students, friends, or (most importantly) to my own children?  I’ll keep some of the lessons I’ve learned private, but here are a few:

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Alcohol, Coffee & Sex: Keeping the Revolution at Bay

To alcohol… the cause of, and solution to, all of life’s problems.” – Homer J. Simpson


I read this essay by Adam Cole on NPR yesterday, titled: “Drink Coffee? Off With Your Head!” Cole explained that in the past some societies viewed the widespread acceptance of coffee drinking as a threat to social order. This was true of England and the Ottoman Empire during the 17th century, as well as in 18th century Prussia.  

The threats came in different forms – in terms of health, spirituality, and political upheaval. Cole reiterated that sometimes coffee was blamed for draining a person’s vigor, at other times painted as “poison for the bodies and souls.” And it was also seen as a sort of lubricant for revolution, since it was consumed in coffee houses where people could discuss a range of subjects, including possibly getting rid of the current social and political status quo.

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Sex and Love in the Long Run


[I hope you like graphs … ]

♪ Now everyone dreams of a love lasting and true, / But you and I know what this world can do. / So let’s make our steps clear, so the other may see./ I’ll wait for you, and should I fall behind, will you wait for me? 

— Bruce Springsteen & Patti Scialfa (“If I Should Fall Behind”)


“Contrary to what has been widely believed, long-term romantic love (with intensity, sexual interest, and engagement, but without the obsessive element common in new relationships), appears to be a real phenomenon that may be enhancing to individuals’ lives—positively associated with marital satisfaction, mental health, and overall well-being.”

— Bianca Acevedo and Arthur Aron (2009: 64)


In the 2013 film “Before Midnight,” we caught up with Celine and Jesse (played by Julie Delpy and Ethan Hawke) who had fallen in love during a chance, whirlwind evening in Vienna eighteen years earlier. After nine years apart between the first and second parts of the trilogy, they have been together for the last nine and are now in their early forties, and have twin girls together as well as a son from Jesse’s first marriage.

The first part of the trilogy, “Before Sunrise,” focused on Celine and Jesse’s incipient romantic connection as they explored the city, talking all night about a variety of topics before ultimately having to separate. In part two they reconnected. By the third film we see that there is still love, but with more complexity within their long-term relationship. We see themes of restlessness, resentments over suspected past infidelities, and the struggles that come with balancing parenting, career, sexual desire, domestic life, and having family spread out over long distances. They lament that passion (for all things) came easier to them when they were younger, and Jesse suggests that maybe “this is the natural human state – always a little dissatisfied, perpetually discontented.” We are left wondering if their relationship will survive.

The New York Times critic A.O. Scott reviewed “Before Midnight” jointly with the European film “Amour,” released the previous year. In that movie, we saw an elderly couple struggling with failing health. Scott pondered why such films, with their focus on a couple already-in-progress, were less common than ones centered around early romance. In his view, the reason is that unlike romantic comedies, marriage “has no story arc.”

“A marriage plot, which is to say a comedy, is a story with a wedding at the end. The exchange of vows provides a satisfying and efficient exit from an intricate story. After the chaos of misbehavior, misunderstanding and missed connection, order is restored, the curtain falls, and love’s essential labor is done. But if the story starts in the middle, sometime after the honeymoon, at the breakfast table or the parent-teacher conference, where then does it conclude? There are only two logical possibilities, both of them sad.”

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Ten Lessons on Love, from the Wise

I started teaching a new class this semester on patterns of human mating. One of our assignments was what we called “Interviews with the Wise.” I asked students to speak informally with older people, asking them what they had learned about sex, love, marriage, and relationships, and what lessons they would like to pass along to young people. We collectively came up with the questionnaire as a class. 

The interviewees ranged in age from their late 50s to their early 90s (‘older’ is always a relative term, I suppose). Most would probably be described as traditional, most were married once, but some were married a few times or none at all. Several were raised Catholic (it is New England), and we had a range of people from different ethnicities.I was very impressed with how seriously the students took the assignment, and how open their interviewees were. 

Below are some of the patterns I noticed from the interviews:

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New Class on Human Mating

This semester, I started teaching a ‘special topics’ class in biological anthropology related to human mating. Special topics classes can shift subject matter from semester to semester, depending on the instructor, but I decided to try to put together some of what I learned from the “Humans Are Blank-ogamous” series into a classroom setting.

The two books I decided to use are  “Evolution and Human Sexual Behavior by Peter Gray and Justin Garcia and William Jankowiak’s edited book “Intimacies: Love and Sex Across Cultures”.  We’ll also read a number of articles by authors from a range of perspectives and disciplines. The thinking is that different authors each have a piece of the puzzle, akin to the parable of the blind men and the elephant. Our goal is to try to describe the elephant.

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The Sex Lives of Others

“Although anthropologists have identified few, if any, true human universals, taboos are widespread against exposure of the genitals, public displays of sexual behavior, and multiple consecutive partners. Having sex willingly in the presence of observers or with multiple participants crosses a line of social propriety in many societies. Where these lines are drawn is, of course, highly variable.”          

– Katherine Frank, Plays Well in Groups: A Journey Through the World of Group Sex (2013: 3)

“Humans aren’t the only sex deviants in the animal kingdom. But we are the only ones to stigmatize each other as disgusting perverts.”

– Jesse Bering, Perv: The Sexual Deviant in All of Us: (2013: 216).


Apes don’t have bedrooms.

This is relevant because privacy is sometimes hard to come by in the life of an ape, including for intimate sexual behavior. But for humans it’s different. Sexual privacy is important, yet privacy is never really absolute.

One of the more puzzling questions around human sexuality is why we invest so much energy into influencing the sexual and romantic lives of other people. Why does it matter to us whether celebrities get divorced, or gay people marry, or whether the sexual behavior of strangers somehow falls outside specific social norms?

This isn’t necessarily the case for our primate cousins. Certainly, monkeys and apes compete for mates and they keep track of each others’ social relationships. What they do not do is moralize about proper sexual practices. For chimpanzees and bonobos (outside of the occasional private tryst away from the group to avoid interference from a dominant male), sex usually takes place in view of fellow group members, with little fanfare. Among bonobos, sex is so common that it is almost mundane.

In one study, Zanna Clay and colleagues observed a group of fifty adult bonobos for about a thousand hours in a year (Clay et al 2011). In that time, they recorded 1,100 female–male copulations and 674 female–female genital contacts. Notably, females often made ‘copulation calls’ when they were with a partner of higher rank, regardless of whether their partner was male or female. Clay suggested that these calls were part of a female’s social strategy, announcing to other group members that they had powerful friends (“Hey, see who likes me!?”).

However, while apes jockey for social position when it comes to relationships, we can take this to another level. Not only do we try to improve our own prospects by climbing the social ladder, but we can also get quite judgmental about others’ erotic lives.

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