Why Is the Penis Shaped Like That?: And Other Reflections on Being Human Read online

  For JCQ

  Contents

  Title Page

  Dedication

  An Invitation to Impropriety

  Part I. Darwinizing What Dangles

  How Are They Hanging? This Is Why They Are

  So Close, and Yet So Far Away: The Contorted History of Autofellatio

  Why Is the Penis Shaped Like That? The Extended Cut

  Not So Fast … What’s So “Premature” About Premature Ejaculation?

  An Ode to the Many Evolved Virtues of Human Semen

  Part II. Bountiful Bodies

  The Hair Down There: What Human Pubic Hair Has in Common with Gorilla Fur

  Bite Me: The Natural History of Cannibalism

  The Human Skin Condition: Acne and the Hairless Ape

  Part III. Minds in the Gutter

  Naughty by Nature: When Brain Damage Makes People Very, Very Randy

  How the Brain Got Its Buttocks: Medieval Mischief in Neuroanatomy

  Lascivious Zombies: Sex, Sleepwalking, Nocturnal Genitals—and You

  Humans Are Special and Unique: We Masturbate. A Lot

  Part IV. Strange Bedfellows

  Pedophiles, Hebephiles, and Ephebophiles, Oh My: Erotic Age Orientation

  Animal Lovers: Zoophiles Make Scientists Rethink Human Sexuality

  Asexuals Among Us

  Foot Play: Podophilia for Prudes

  A Rubber Lover’s Tale

  Part V. Ladies’ Night

  Female Ejaculation: A Scientific Road Less Traveled

  Studying the Elusive “Fag Hag”: Women Who Like Men Who Like Men

  Darwin’s Mystery Theater Presents … The Case of the Female Orgasm

  The Bitch Evolved: Why Are Girls So Cruel to Each Other?

  Part VI. The Gayer Science: There’s Something Queer Here

  Never Ask a Gay Man for Directions

  “Single, Angry, Straight Male … Seeks Same”: Homophobia as Repressed Desire

  Baby-Mama Drama-less Sex: How Gay Heartbreak Rains on the Polyamory Parade

  Top Scientists Get to the Bottom of Gay Male Sex Role Preferences

  Is Your Child a “Pre-homosexual”? Forecasting Adult Sexual Orientation

  Part VII. For the Bible Tells Me So

  Good Christians (but Only on Sundays)

  God’s Little Rabbits: Believers Outreproduce Nonbelievers by a Landslide

  Planting Roots with My Dead Mother

  Part VIII. Into the Deep: Existential Lab Work

  Being Suicidal: Is Killing Yourself Adaptive? That Depends: Suicide for Your Genes’ Sake (Part I)

  Being Suicidal: What It Feels Like to Want to Kill Yourself (Part II)

  “Scientists Say Free Will Probably Doesn’t Exist, Urge ‘Don’t Stop Believing!’”

  The Rat That Wouldn’t Stop Laughing: Joy and Mirth in the Animal Kingdom

  Notes

  Acknowledgments

  Index

  Also by Jesse Bering, Ph.D.

  About the Author

  Copyright

  An Invitation to Impropriety

  For as long as I can remember, I’ve been sincerely curious, and vocally so, about certain “inappropriate” matters. My most earnest questions, I’ve noticed, tend to cause other people to back away from me very slowly. You might say I’m a little too analytical for my own good. “Isn’t it unusual,” I asked the absolutely horrified girl sitting next to me in my sixth-grade homeroom class one memorable day, “that my penis, when erect, is shaped more like a scimitar than a dagger? Certainly that must mean I’m deformed,” I confided, whispering in her ear, “since obviously to penetrate a female like you properly, a penis must go straight into a vagina, not approach it from a forty-five-degree angle, as mine stands.” Over time, I learned to bite my tongue. But a salacious mind, once stirred, seldom gets rest.

  As I very slowly gained some much-needed social skills, I also found myself gravitating increasingly toward the world of science, a world in which nothing was sacred, no question too absurd or off-limits (at least for the sake of discussion, if not necessarily ethical fodder for the laboratory), and one in which I discovered other like-minded souls who didn’t look at me as though I had three heads when I asked whether, say, people who prefer to be the recipient in anal intercourse might have a differently configured anal-genital internal anatomy than those who find it intensely unpleasant. I still don’t know the answer to that question, by the way.

  Speaking of which, I should probably also add (since it will become obvious enough by my disproportionate focus on male genitalia) that there was something very important to me that was denied full expression in my earlier years and that undoubtedly shaped my view of the world. I was gay. Very, very gay, in fact. I confirmed this incontrovertible truth through numerous experiments in my adolescence, including groping and kissing unwitting “girlfriends,” who, in spite of their objective good looks and wonderful personalities, were as arousing to me as a perfumed slab of ham with sparkling white teeth. This wasn’t just the virginal jitters, I can assure you, but girls seemed to make my penis positively catatonic, while even from afar boys made it stand at that oddly forty-five-degree angle I mentioned before.

  So, let me start by offering a full disclosure: my perspective is that of a godless, gay, psychological scientist with a penchant for far-flung evolutionary theories. Still, although I certainly don’t try to hide my own personal convictions, I’m an impolitic person. All I ask is that you try to suspend judgment until after you’ve read at least a handful of essays. Just lean back, unbutton your pants, and, by all means, get comfortable with yourself. Maybe relax with a glass of Chardonnay. And think. I hope to make that last part easy for you. I want you to enjoy learning about your wildly ejaculating penises, your dribbling vulvae, and your own fears, biases, fetishes, and desires. Despite our differences, and there are certainly many in this world, there’s one thing we all have in common: we’re human.

  I’m not interested in sensationalism for its own sake, but many of the questions that appeal to me most are, by definition, rather sensational. If you look at them closely enough, however, you’ll notice how often the most titillating topics are uniquely able to raise deeper philosophical questions and to bring much more substantial issues to the surface. For instance, in reading about zoophiles, you may find yourself, as I did, questioning your own knee-jerk moralistic sexual repulsions; a look at the evolution of pubic hair or acne unexpectedly reveals our close genetic relationship with other apes; masturbation fantasies reveal what makes us unique in the animal kingdom; and foot fetishists expose how our adult turn-ons are permanently calibrated by often-innocent childhood experiences.

  I do try to be a good scientist first and foremost, whether I’m investigating female ejaculation, six-month-old infants unexpectedly sprouting pubic hair, or the psychology of women curiously entranced by gay men. Since many of these essays were published originally, in some form, in my columns at Scientific American and Slate magazines, and therefore survey only the most interesting dimensions of any given topic, I’m certainly not able to cover every aspect and contrary viewpoint surrounding every issue. I encourage you, however, to read further about the subjects that leave you wanting more, and for that purpose I’ve included endnotes to help get you going.

  So, please, join me in impropriety. Let’s not subscribe to the some-things-are-better-left-unsaid school of life. How very boring that must be. I invite you to follow along with me on a journey of scientific discovery. Feel free to dip in and out in your reading or read the essays out of sequenc
e. Each stands alone. But do watch your step: it’s a slippery one. And note that although the mood is for the most part light, it won’t be all fun and games. Some of the essays I’ve included in this anthology are actually rather sobering—including a really close look at the mind-set of a suicidal person. I wrote that particular piece in response to the alarming rash of gay teen suicides in recent years. That was an article that resonated, and unfortunately so, with many readers, some of whom courageously shared their personal stories with me after stumbling upon it.

  There are eight sections in this volume, each one representing a general theme or subject area and sampling the astounding oddities of simply being human. The first of these sections, “Darwinizing What Dangles,” includes everything you didn’t know you always wanted to know about male reproductive anatomy. In part II (“Bountiful Bodies”), we’ll examine how we may be designed by Mother Nature to consume each other’s flesh, why we’re the only ape that suffers from acne, and many other little-known things about seemingly banal body parts. Next, in part III (“Minds in the Gutter”), we’ll explore some very dirty brain science, pushing our common sense into a few uncomfortable corners in the process. This prepares us for part IV (“Strange Bedfellows”), where we’ll take a critical, nonjudgmental look at some of the more intriguing sexual paraphilias, fetishes, and conditions, exploring their developmental origins, theories, and debates regarding clinical diagnoses. If you think having sex with animals is inherently wrong, or that sexuality starts in adolescence with the first flush of hormones, you may come away from this section with an unexpected change of mind.

  In “Ladies’ Night” (part V), we’ll turn our attention specifically to the minds and bodies of women. Just note that I’m a gay man looking into and at these minds and bodies, so my take is a bit different from most. Speaking of which—and I’m not sure what Nietzsche would have to say about the content of the following section—in part VI (“The Gayer Science: There’s Something Queer Here”), we’ll then focus on some of the latest and most provocative studies on homosexuality. In part VII (“For the Bible Tells Me So”), we’ll examine how religion stems from our evolved psychology and how our standard burial practices aren’t doing ourselves or the planet any favors. And finally, in the last section of the book, “Into the Deep: Existential Lab Work,” we’ll dig into some weighty, soul-wrenching questions about suicide, the meaning of life, and the evolution of joy and happiness.

  Excited? I hope so. And what better place for us to start than by asking why in the world testicles hang like that—and why does it hurt so much to get kicked there?

  PART I

  Darwinizing What Dangles

  How Are They Hanging? This Is Why They Are

  A few years ago, the evolutionary psychologist Gordon Gallup, whom we’ll meet again later in this section, along with his colleagues Mary Finn and Becky Sammis, set out to explain the natural origins of the only human male body part arguably less attractive than the penis—the testicles. In many respects, their so-called activation hypothesis elaborates on what many of us already know about descended scrotal testicles: they serve as a sort of cold storage and production unit for sperm, which keep best at a temperature slightly lower than the norm for the rest of our bodies. But the activation hypothesis goes much further than this fun fact.

  It turns out that human testicles display some rather elaborate yet subtle temperature-regulating features that have gone largely unnoticed by doctors, researchers, and laymen alike. The main tenet of the activation hypothesis is that the heat of a woman’s vagina radically jump-starts sperm that have been hibernating in the cool, airy scrotal sac. This heat aids conception. Yet it explains many other things too, including why one testicle is usually slightly lower than the other, why the skin of the scrotum sometimes becomes rugose (prune-like and as wrinkled as an elephant’s elbow), why the testicles retract during sexual arousal, and even why testicular injuries—compared with other types of bodily assaults—are so excruciatingly painful.

  To help us all get on the same page, consider an alternate reality, one in which ovaries, like testicles, descend during embryological development and emerge outside the female body cavity in a thin, unprotected sac. After you’ve wiped that image from your mind’s eye, note that the dangling gonads of many male animals (including humans) are no less puzzling. After all, why in all of evolution would nature have designed a body part with such obviously enormous reproductive importance to hang outside the body, so defenseless and vulnerable? We tend to become accustomed to our body parts, and it often fails to occur to us to even ask why they are the way they are. Some of the biggest evolutionary mysteries are also the most mundane aspects of our lives.

  So the first big question is why so many mammalian species evolved hanging scrotal testicles to begin with. The male gonads in some phylogenetic lineages went in completely different directions, evolutionarily speaking. For example, modern elephant testicles are deeply embedded in the body cavity (a trait referred to as testicond), whereas other mammals, such as seals, have descended testicles but are without scrota, with the gonads simply being subcutaneous.

  Gallup and his colleagues jog through several possible theories of our species’ testicular evolution by descent. One of the more fanciful accounts—and one ultimately discarded by the researchers—is that scrotal testicles evolved in the same spirit as peacock feathers. That is to say, given the enormous disadvantage of having your entire genetic potential contained in a thin satchel of unprotected, delicate flesh and swinging several millimeters away from the rest of your body, perhaps scrotal testicles evolved as a sort of ornamental display communicating the genetic quality of the male. In evolutionary biology, this type of adaptationist account appeals to the handicapping principle. The theoretical gist of the handicapping principle is that if the organism can thrive and survive while still being hobbled by a costly, maladaptive trait such as elaborate, cumbersome plumage or (in this case) vulnerably drooping gonads, then it must have some high-quality genes and be a valuable mate.

  But the handicapping hypothesis doesn’t quite fit the case of descended scrotal testicles, explain the authors, because if it were true, then we would expect to see these body parts becoming increasingly elaborate and dangly over the course of evolution, not to mention that women should display a preference for males toting around the most ostentatious scrotal baggage. “With the possible exception of colored scrota among a few species of primates,” writes Gallup, “there is little evidence that this has been the case.” I’m not aware of any studies on intraspecies individual variation in scrotal design, but I’m nonetheless willing to speculate that most human males have rather bland, run-of-the-mill scrota. Anything deviating from this—particularly a set of unusually pendulous testicles suspended in knee-length scrota—is probably more likely to have a woman dry heaving, screaming, or staring in confusion rather than serving as an aphrodisiac.

  Again, a more likely explanation for scrotal descent, and one that has been around for some time, is that sperm production and storage are maximized at cooler temperatures. “Not only is the skin of the scrotal sac thin to promote heat dissipation,” the authors write, “the arteries that supply blood to the scrotum are positioned adjacent to the veins taking blood away from the scrotum and function as an additional cooling/heating exchange mechanism. As a consequence of these adaptations average scrotal temperatures in humans are typically 2.5 to 3 degrees Celsius lower than body temperature (37 degrees Celsius), and spermatogenesis is most efficient at 34 degrees Celsius.”

  Sperm are extraordinarily sensitive to even minor fluctuations in climate. When the ambient temperature rises to body levels, there is a momentary increase in sperm motility (they become more lively), but only for a period of time before fizzing out. To be more exact, sperm thrive at body temperature for fifty minutes to four hours, the length of time it takes for them to journey through the female reproductive tract and fertilize the egg. But once the spermatic atmosphere rises
much above 37 degrees Celsius, the chances for a successful insemination consequently plummet—any viable sperm become the equivalent of burned toast. So in other words, except during sex, when it’s adaptive for sperm to be hyperactive, sperm are stored and produced most efficiently in the cool, breezy surroundings of the relaxed scrotal sac. One doesn’t want his scrotum to be too cold, however, since nature has calibrated these temperature points at precisely defined optimal levels.

  Fortunately, human scrota don’t just hang there holding our testicles and brewing our sperm; they also “actively” employ some interesting thermoregulatory tactics to protect and promote males’ genetic interests. I place “actively” in scare quotes, of course, because, although it would be rather odd to ascribe consciousness to human scrota, testicles do respond unintentionally to the reflexive actions of the cremasteric muscle. This muscle serves to retract the testicles so they are drawn up closer to the body when it gets too cold—just think cold shower—and also to relax them when it gets too hot. This up-and-down action happens on a moment-to-moment basis; thus male bodies continually optimize the gonadal climate for spermatogenesis and sperm storage. It’s also why it’s generally inadvisable for men to wear tight-fitting jeans or especially snug “tighty whities”; under these restrictive conditions the testicles are shoved up against the body and artificially warmed so that the cremasteric muscle cannot do its job properly. Another reason not to wear these things is that it’s no longer 1988.

  Now, I know what you’re thinking. “But, Dr. Bering, how do you account for the fact that testicles are rarely perfectly symmetrical in their positioning within the same scrotum?” In fact, the temperature-regulating function governed by the cremasteric muscle can account even for the most lopsided, one-testicle-above-the-other, waffling asymmetries in testes positioning. According to a 2009 report in Medical Hypotheses by the anatomist Stany Lobo and his colleagues, each testicle continuously migrates in its own orbit as a way of maximizing the available scrotal surface area that is subjected to heat dissipation and cooling. Like ambient heat generated by individual solar panels, when it comes to spermatic temperatures, the whole is greater than the sum of its parts. With a keen enough eye, presumably one could master the art of “reading” testicle alignment, using the scrotum as a makeshift room thermometer. But that’s just me speculating.