In his new book, If Our Bodies Could Talk, James Hamblin, an MD and senior editor at The Atlantic, answers some key queries about the human body. Here's a preview.
Why are nipples sexualized?
In Poland—where female toplessness is illegal—anthropologists Agnieszka M. Zelazniewicz and Boguslaw Pawlowski have extensively studied the nature of human attraction to breasts. They write in one academic journal that "large female breasts should be perceived as attractive" to heterosexual males because they may signal an ability to bear children. Infants do not spring forth from breasts, but females with low waist-to-hip ratios and large breasts tend to have higher levels of the hormone associated with fertility. "Large breasts may also be a cue for better genetic quality," write the anthropologists.
Still, in their research it was not the case that bigger was better. To men, the most attractive bra sizes were C and D, beating out the smaller A and B, but also the still larger E. The anthropologists estimate that as breast size increases during pregnancy and lactation, "there is a possibility that breasts that are too large signal that a woman is not fertile at the moment and, therefore, less attractive, especially for short-term mates." They suggest that men may also discriminate against the largest-breasted women "due to anticipated infidelity," as other research has shown that females with large breasts are perceived as being more promiscuous and "sexually open." Females with smaller breasts are perceived not only as moral and mod- est but also as competent, ambitious, and intelligent. Other researchers have found that male preference for larger-breasted women can be even more deeply arbitrary, in one study coming down to whether or not men were hungry at the time that they expressed their preferences between two bust profiles. This is part of a resource-scarcity hypothesis, wherein males with tenuous access to the basic needs of daily life tend to prefer females with larger breasts.
After spending two years topless in New York City, Holly Van Voast is at once more universal and more succinct in her wisdom: "Look, everyone loves tits. They're alluring. We're taught to look for them as babies. People are programmed to love them." She uses the term cognitive dissonance every few sentences when telling stories about all the people who took serious and sometimes violent offense at her breasts on the subway or in the park. The worst reaction was a woman with a child who shoved Van Voast into a police barricade. "Acting like you hate them anywhere is absurd. I'm not a lesbian, but they're alluring."
When men took offense, they would often draw an analogy to their own penises. Something to the effect of "What if I went around with my dick hanging out?" Van Voast was struck by how often people drew analogies to penises. The penis-boob equivalence is cultural rather than anatomical; the anatomic analogy would be the clitoris. She came to understand the sexualization of breasts as a projection of male psychology. With sexualization of any body part comes timidity and judgment, a result of pervasive suppression of sexuality. This has tangible health effects. For example, breast reduction surgery remains more common than breast augmentation surgery, and is proven to be effective in treating and preventing back and neck pain, improving a person's quality of sleep and ability to exercise. Still, because of the stigma around all breast surgery, reduction is often not covered by insurance. To truly solve the nipple disparity, Van Voast has concluded that women need not march on Washington topless, as in the popular Free the Nipple campaign, but simply go topless around their neighborhoods in their daily lives. Though it will require fortitude. Nipple activists, she says, are "swimming to the surface of history's burdens on women to absorb amazing amounts of ridicule and abuse." But she is uniquely equipped to deal. "I have the ability to process these things, and most women don't. I don't know why. I don't know why. It's like I'm the Turing of tits."
Still, despite her powers, she gave it up in 2013. The cognitive dissonance was unbearable. She won $77,000 in a lawsuit against the NYPD for multiple wrongful arrests and moved upstate to Schenectady. "There are huge power struggles in our society," she explained, "and the topless thing was just a way of seeing these things in a more obvious manner."
Why do penises look like penises?
Why the shaft and glans of the human penis are so much larger than the shaft and glans of the clitoris has long been a sort of unquestioned curiosity. One book that made important headway into understanding why penises have a bulbous glans at the end—instead of just being a nondescript cylinder, or even a hollow cone of the sort that is used during artificial insemination—is journalist Jesse Bering's Why Is the Penis Shaped Like That? In it, he describes Semen Displacement Theory.
As anyone who has spent more than a few minutes on YouTube knows, many animals have penises. Not many of them use the penis to thrust in and out as persistently or as aggressively as the human male, though. Part of this is born of tradition and the unimaginative male mind. But part of it is physiologic demand. Why should it feel good to males and females when the penis is thrust in and out? Why not, like a lion, just let it sit in there, remaining perfectly still, until it does its penis thing and deposits semen? The reason might be the same as that for the glans's bulbous shape. Semen Displacement Theory posits that the helmet and the coronal ridge, combined with repeated thrusting, serve to pull semen out of the vaginal canal. And why do that? For the same reason males do so many things: because mating is a competitive sport. The idea is that another male might have recently deposited semen in this particular female's vagina. The job of the male and his penis, then, is twofold: to deposit his own semen, yes, but also to remove all other semen in the process.
If ever there were a physiologic argument against monogamy, it might be Semen Displacement Theory. In this way, a larger penis is advantageous for the romantic reason that it's more effective as a sort of semen shovel.
Psychologist Gordon Gallup at the University of Albany tested the mechanics of this theory. Not by having people have unprotected sex with multiple partners in succession. He used prosthetic penises. And it did seem to work. One might wonder: Couldn't this be counterproductive, in that a penis might end up removing its own semen? That's unlikely, because contrary to so many lyrical allusions to "making love" for periods lasting "all night long," most erections dissipate shortly after ejaculation. This fact is less popular in song, as is the fact that the post-ejaculation penis tends to become averse to further stimulation. What was moments ago pleasurable—to a degree that males would go to tremendous lengths to achieve—becomes disagreeable.
If Semen Displacement Theory holds, this would make sense from a reproductive standpoint. The male should want to keep his semen remover away from his deposit, lest his work be undone. Maybe best for him to just fall asleep.
When is ejaculation premature?
The average duration of heterosexual human intercourse is three to thirteen minutes, usually ending when the male ejaculates and becomes lethargic. Other species do not spend even this much time. Lions average less than one minute. Marmosets ejaculate within five seconds of penetration. If you talk to marmosets, they say all the better to get back to hunting and protecting their families from predatory birds.
Still, shouldn't natural selection favor the males who most quickly deposit "the goods"? (And should we ever refer to semen as "the goods"?) If you believe in Semen Displacement Theory as an explanation for the absurd shape and size of the male penis, then a lengthy thrust session may be a subconscious instinct to thoroughly scour the vaginal canal. Then, and only then, should one deposit the goods. Alan Dixson, a professor of biology at the University of Wellington in New Zealand, has indeed posited this explanation for the human predilection for prolonged sex with "patterns of deep thrusting."
Why don't males have multiple orgasms?
At the Marriott in downtown Charleston, South Carolina, scientists gathered for the 2016 meeting of the International Society for the Study of Women's Sexual Health. There researchers reported findings from the largest nationally representative study of, as they referred to it, "women's pleasure." It's not an attempt to sidestep the word orgasm, but to carefully note that a contraction of muscles in the pelvic floor is not the sole element of what's pleasurable about sex. Researcher Debby Herbenick of Indiana University's famed Kinsey Institute assured me that women can have pleasurable experiences without an orgasm.
It was Alfred Kinsey himself—who came to Indiana to study wasps and ended up the world's premier researcher of human sex habits—who reported in his 1953 book Sexual Behavior in the Human Female that most human females have the capacity for multiple orgasms. To the scientific community at the time (mostly men), this was a revelation. Virginia Johnson and William Masters at Washington University in St. Louis would go on to turn Kinsey's survey into hard evidence. In a lab, women stimulated with a vibrator would often have several orgasms within minutes. Some had as many as fifty.
The Study of Women's Sexual Pleasure involved three years of in-depth interviews with more than two thousand women and found that today 47 percent of women have had multiple orgasms. "Our sense is that it's possible in more women," Herbenick told me, "but it's often a partner issue. Some women become too sensitive to continue after an orgasm. Others have one orgasm and are like, 'That's sufficient.'"
After the first orgasm, she explains, most females find that different techniques build to the second. Because sensitivity is so heightened after the first orgasm, the exact same motion can be uncomfortable or even painful. It's a mistake to take that as a sign that someone isn't capable of multiple orgasms, only that they will arise in a different way. A second, third, or fortieth consecutive orgasm is usually not a result of increasing intensity, but of less direct pressure and slower movement. While it's common for females to have this capacity, most males have a refractory period. There are, though, Herbenick tells me, "a handful of men" who "can keep having erections to the point of ejaculation one after the other." In those cases, though, the sperm count in subsequent ejaculations falls dramatically. These are not functional ejaculations, but ejaculations of pride and indulgence. If a male has the capacity to orgasm repeatedly, there would be no logic in it from a functional biology perspective. The body has almost no capacity to store more than one load of sperm at a time. Inside the body, sperm die and mutate quickly. The testicles must hang below the body because sperm can be produced only at temperatures slightly below that of the human body. Once produced, sperm can be stored only in limited quantities and live only a few days. So, why would a male have multiple orgasms if only the fit one can produce enough sperm to lead to pregnancy? The real limiting factor is the tenuous life of sperm. Guys, if you want multiple, rapid-fire orgasms, evolve a better system for storing sperm. Maybe it is a sack that is sewn to the perineum? I don't know. This is why there are venture capitalists.
Females, subject to no such problem storing gametes—their eggs are present and stored away since infancy—should be free to orgasm endlessly. Yet, Herbenick and many others lament, this potential is often unrealized. The common difference between females who are sexually thriving and those who are not is less often physiological than social. Women who feel like they can talk comfortably and explicitly with their partner are far more often satisfied. While multiple orgasms are great, Herbenick's urgent point is that when unsatisfying sex becomes the norm, it warrants discussion. The study also found that women who felt that they could talk with their partners specifically about what makes sex pleasurable for them are eight times—eight times— more likely to be happier in their relationships. Again: eight times. A culture where talking about sexual pleasure is taboo cannot earnestly espouse "family values." As Herbenick put it, "A major family value would be talking explicitly about sexual pleasure."
From IF OUR BODIES COULD TALK by James Hamblin
Copyright © 2016 by James Hamblin
Published by arrangement with Doubleday, an imprint of The Knopf Doubleday Publishing Group, a division of Penguin Random House LLC