I recently went dancing with my wife at an upstairs ballroom, and was pleased to discover that “club music,” what I once called “Euro-disco” and don’t particularly like, is happily and compulsively danceable. My wife will dance to anything, and normally has to wait for the right song, or has to buy me a shot of some spirit, to get me out on the floor. I was surprised at first that most of the early dance crowd was women, who my wife informs me often go out to dance when their consorts, male or otherwise, will not. There’s a song by a band called Garbage (from their album “Bleed Like Me” with the line, “The boys want to fight. The girls just want to dance all night.” The boys show up on the dance floor later, but most can't dance.
What pleased me however was the entire absence of a disturbing cultural phenomena called “grinding,” which may have been in its last gasp already when Miley Cyrus made “twerking” infamous. There was a semester at the college I once taught where weekly dances were cancelled as the “grinding” had produced some disturbing detritus on the sweaty dance floor. When I introduced a feminist critique of “grinding” in a social psychology class, one of my students told me they started learning how to do this in Junior High School.
Now, don’t get me wrong, I am well aware that there are a range of gender and sexual identification variations between stereotypically “male” and “female” body shapes, clothing, and behavior, but even these have been addressed by empirical research in evolutionary psychology, and have their own place in biological evolution. There is a wonderful trade book written by a scientific expert by the name of Robin Baker (1998, revised in 2006), called Sperm Wars, that provides an accessible and non-scholarly account of “Infidelity, Sexual Conflict, and Other Bedroom Battles.”
We can start with one of the first and most obvious differences between genetically male and genetically female body types, despite a wide range of variation. Nobody who is genetically male has yet given birth to a child, and genetic females tend to have the wider pelvis and hips which make it possible to give birth to infants with such large brains. Not that this is easy. During most of history, roughly 50% of adult female deaths were the result of childbirth. You can go onto many cemeteries with graves from the early 20th century or before, and find examples of families of men with serial wives, their graves marked amidst the births and stillbirths of the children they bore. So yes, women tend to have wider hips than men, especially women who successfully bear children, living examples of which, yes, also have the gluteal musculature necessary for bipedal gait with a wider pelvis. Moreover, since bipedal gait requires moving one’s center of gravity over the support leg, while the second leg swings forward, female gait does tend to include wider pelvic oscillations. Anyone wanting to mimic a female gait can do so by a wider sway of the hips, and women can also exaggerate this sway to draw attention to this bodily variation. Men tend to have heavier musculature in the upper torso, and wider shoulders, which are interestingly enough, one of the last things to develop in adolescents, as this is a marker of adult bodily form, and therefore of greater threat. The best book I have read in decades on human development is a 900 page tome by Melvin Konner called The Evolution of Childhood (2010). This shoulder width variation can also be exaggerated in males interested in masculine display, exemplified by the so-called “athlete’s swagger.”
That men and women tend to have different body types, and will, of mechanical necessity, have different patterns of gait is hardly controversial. What is interesting, however, is how these and other uncontroversial biological differences between the two most common sexes can actually provide some interesting ways of understanding a much wider range of behavioral differences, particularly those having to do with sexuality and reproduction. Much of this is the subject matter of a mushrooming empirical literature in evolutionary psychology, but some of the perspectives suggested on human behavior, though sometimes controversial, can be related directly to uncontroversial biological facts, though puritan cultures tend to discourage asking relevant questions. For example, if a male is to reproduce, he will need a reproductively viable female. It turns out that regardless of whether a culture prefers thin or more ample women (the latter more appealing in a subsistence culture), a ratio of waist to hips of .7 tends to be the most appealing, as is the pelvis width for reproduction.
Part of “grinding” for example, might certainly be that this is a clear and obvious emphasis on a woman’s pelvis, musculature, and motion. In my dotage, my uncorrected vision tends to be a bit blurry, but even without my glasses, when I cannot really see the outline of a body, or the character of its curves, all it takes to grab my attention on a beach, is a particular pattern of gait, and I can perceive that motion even when what is making that motion is a blur. Availability for “grinding” would certainly get a man’s attention, and, as I understand it, provide him with a certain amount of stimulation. What is less clear to me, however, is what a woman gets out of it, though I suppose male attention is certainly part of it, but it isn’t the kind of attention one gets from a smiling face-to-face conversation.
That women bear children and men do not leads to some interesting, and perhaps obvious differences. I’ve already mentioned the risks of childbirth, for most of the human lineage, something that is likely to contribute to a woman’s being more careful about engaging in the behavior leading to such an event. That, and the fact that a pregnancy, childbirth and child-rearing also taxes biological resources far more for a woman than for a man. One of my favorite “bad girl” feminists, Camille Paglia, once famously said that a man’s contribution to childbirth is a “gob of refuse.” He certainly has substantially less at stake, at least bodily and biologically, than a woman does. Higher risk means more caution, and this does not require conscious thought. Some of the male-female differences in both speed of arousal and tendency to risk-taking may be biological adaptations to this reproductive difference.
When I was teaching, I made a practice of drawing two overlapping bell curves when addressing gender differences in behavior, as it is almost never the case that women do one thing and men do another. Since most human behavior is the product of a range of factors, many abilities, from intelligence on down, take the form of a bell curve. In many ways this is a simple and direct product of statistical variation, as anyone who has ever played backgammon, or even rolled dice, knows. There are a lot more combinations of two dice that will result in a seven, than a two, or a twelve, so if you graphed their likelihood, you get something like a bell curve. It is easier to see this with a Quincunx board (or Galton board), where you drop little balls through a rows of pegs, where at each peg, a ball can go either way, ending up in a row of trays at the bottom. Since there are more ways to get to central positions, when you drop a series of balls through the pegs, you’ll have more in the central positions. Hence a bell curve.
Now what if we had two kinds of balls, little pink estrogen balls, and little blue testosterone balls, and the blue ones were just a little bouncier, so they tend to bounce a little further. A curve made from running the blue ones through the Quincunx is going to have a lower peak, and spread out further (a variation in what is called kurtosis). Kind of what you would get in a distribution of performances, more risk producing more extreme scores on both ends. You may find more males at higher levels of performance, more CEOs and senators, but also at the other end: More violent deaths, and more prison incarcerations. You don’t get just one end. Might say a lot about gender differences, don’t you think? So not only are the curves for the boys and those for the girls overlapping, but they spread differently. If women have more biologically invested in offspring, it makes sense to take fewer risks. Unlike idiot men.
The biggest difference between the sexes pointed out by evolutionary biology is that of “parental investment.” Clearly, the one who has the more obvious investment is the one bearing the child, as her body is tied up for forty weeks, more, as my wife points out, given recovery, and return to some semblance of hormonal normalcy. The pregnancy also gives mommy a big head start on bonding with the child, knowing its rhythms, and movements. Women only have finite ova, and the number of children possible is also limited by the shorter time between menarche and menopause than between spermarche and, well, death. Not having to actually bear the children and having sperm to waste, the male reproductive ceiling is higher. Ismail ibn Sharif, the Alaouite sultan of Morocco, had at least 867. Genghis Khan may have fathered 1000-2000 children and is the male progenitor of .5% of the world’s population.
Again, there’s also the historical risks of pregnancy. So a woman has a greater biological investment, even if cultural divisions of labor don’t increase this further. So she has a whole lot more at risk. There’s also the matter of feeding and provisioning the child. Female mammalian predators, for example, tend to be better hunters, as males’ contributions are minimal. Not for human beings, where the male’s contribution is crucial for the extended childhood necessary for training that huge brain, and developing the skills and capacities for handling the levels of social interdependency which are part and parcel of human socialization and enculturation. Overlapping childrearing also makes human beings the only apes not at the verge of extinction, but also requires additional provisioning. So, again, this is going to make the mother far more cautious about who she is getting to help her, from fertilization to college years and beyond.
A male’s attraction to a possible mating partner may more heavily weight the appearance factors that signal fertility and the ability to bear and raise a child. The one bearing the child had better do some serious assessment of longer-term prospects, the commitment of and resources potentially available to her possible partner. Too much may get made of this stuff, because human males and females are far more similar and far more mutually involved in child-rearing than in any other species. It simply is not true that this is what makes women “sex objects” and men “wallet objects.” Data on mating preferences, for example, show that men and women both weigh physical attractiveness behind a number of other features, and don’t weigh it much differently, The only real difference, and it is relative, is the importance of looks versus the ability to acquire and the willingness to share resources (competence, education, surplus wealth). For women these are both important, but for men the latter are further down on the list of priorities. Might this simply be due to differences in power and economics between men and women (the structural powerlessness hypothesis)? Certainly, and in more egalitarian cultures these are reduced, but they are still in the same direction. Moreover women who already have wealth tend to seek men who have even more, and men from the other end of the socioeconomic scale still don’t rate a woman’s other resources very heavily.
Parental investment differences are going to play out in relative differences in sexual strategies for men and women. In one study, male and female experimenters would approach members of the opposite sex on a college campus and say “Hello, I’ve noticed you around campus and find you very attractive,” and then one of three questions, like: 1) “Would you like to join me for a cup of coffee?” 2) “Would you like to join me for dinner at my apartment tonight?” 3) “Would you like to go somewhere to have sex?” On the coffee question, you’ve got a 50/50 chance with either sex. On the question of dinner, 69% of men agree to join a woman for dinner, 6% of women agree to dinner with a man. On question 3, 75% of men agree, but virtually no women. Men are far more likely to agree on sex than to join you for coffee. There’s an old joke on children playing on the playground. One day a boy shows a little girl his penis, and says “I have one of these and you don’t,” and she runs away. The next day he does it again, but this time she raises her skirt and shows her private part: “My mommy says that with one of these, I can have as many of those as I want.”
Note that variations produced by biological evolution need not be part of conscious experience, or reasoned cognition. The distal evolutionary stimuli may well have a variety of proximal expressions. Some of these are “epigenetic,” like the tendency of a girl without an adult male presence in her household to go through menarche and become sexually active at a younger age. Proximal expressions can also differ by culture and historical era. Again, biologically evolved tendencies do not require conscious thought. For example, there is some evidence that men are more likely to mistake a woman’s friendly behavior as indicating more intimate attraction, but this is more an unconscious bias in judgment than an error in conscious intent. Indeed, such a bias may even be made more effective when it is actually at odds with conscious intent. Women may have the opposite bias, and both may use the biases of the other unconsciously. Forgive my obvious sexism, but I have seen plenty of undergraduate woman dress far more provocatively than they perhaps intend, though they should be free to dress however they please. All of the above still jointly suggest that there are going to be advantages on both sides to “getting to know someone” better, which is likely to require not only the social skills of judging intent and desire (which aren’t necessarily the same), but extended face-to-face, full frontal interaction, even joint activity with a potential consort.
Evolution has also produced another rather large difference between human and other mammalian mating strategies, including the biological differences to support them. For most mammals, even for most apes, mating is pretty much a free-for-all. An ovulating female goes into “heat,” and there are hormonally driven physical changes that males are co-evolved to respond to with some enthusiasm. Anyone who has ever seen the consequences of an unsterilized female dog or cat left out in the open understands this pretty clearly. The female gives scent cues available to males for some distance, and her bodily swellings and changes give even stronger cues when distances are decreased. So there are a lot of males around “competing for the favors of a female” as my adult son used to surmise even as a child, when asked about fights between male animals. And mating is almost always “doggie style,” from behind, so cues available from behind will be more important at shorter distances. Sort of like in “grinding.” Except it only occurs during peak fertility at ovulation. Is it only me who was embarrassed as an adolescent in mixed company when we saw animals mating on a farm, or worse, the appearance of swollen, red, and wet labia of a female chimp at the zoo?
For human beings, the evolutionary pressures of extending childhood, and of the complex social interdependence required for survival, preclude the conflicts inevitable in mammalian mating. Moreover the pair-bonding important for long-term provisioning of offspring is not likely to survive females going into heat on a monthly basis. One part of the solution is called “epigamic differentiation,” where, instead of females in heat changing in ways effecting any male, they would be selectively appealing to a smaller number of males, themselves with more particular preferences. But the biggest change is “concealed ovulation,” where a female undergoes far fewer obvious physiological changes during ovulation. Nevertheless, to sustain male interest, many of the cues can be made more permanent features of secondary sexual characteristics, and non-reproductive sexual behavior be extended to the entire monthly cycle.
Think about it. What helps front-to-front communication and social interaction includes obvious features like a face designed to broadcast emotion, including decreases in facial hair, and the existence of a chin and a forehead not found in other animals, with 42 fine muscles on either side of the face which do not move bones, but facial skin and other connecting tissue. Certainly the emergence of language, and communication about non-present objects and events, is going to be facilitated by “face-to-face” interaction.
How much of our full-frontal interaction is about sexuality (and its extension well beyond ovulation), and is facilitated by the emergence of sexual signals that are more differentiated, permanent, and brought around to the front of the body, also facilitating the full-frontal sexual interactions absent in the rest of the mammalian kingdom? Hmm… dare we think about the swollen labia of the chimp in heat? Wait, “labia” is Latin for lips, duh. Human faces also have another orifice surrounded by lips, which no other animals have. Might this be one of the changes? So, um, if a human female wants to look sexy, might she, short of collagen injections to increase swelling, just pinch her lips a little, or pout them out? How about color them with red lipstick, all the better if glossy?
What are breasts for? To feed babies, right? Wait a second, yes, mammary glands are for feeding babies, kind of a defining characteristic of being a mammal, no? But human beings are the only mammals that have external fatty deposits around them. What are those for? Really? Were you never in junior high school? From whom do the development of breasts guarantee substantially more attention, if not the kind of attention that an innocent young nubile really needs? What signal from the rear of an animal in heat might these mimic? Do we have to talk about grinding again? What might those larger pelvises, necessary for giving birth to large brained offspring, and resulting in a particular swaying gait, look like from behind if not two gluteal globes, pressed against each other with a cleavage between them? And what are “push-up” bras designed to do? Is it the cleavage? But yes, how about making those full-frontal interactions far more interesting? Plus, as my biologist wife is wont to point out, “If they are coming toward me, I know if I’m getting their attention. If they are looking at me from behind, however much they may enjoy the view, it doesn’t do much for me.” So what does grinding do for the woman so presenting herself? I still don’t know. I think it’s about what the boys want.