Surprisingly, Rupp said, “Men looked at the female face much more than women, and both looked at the genitals comparably.” Men were also more likely to look at faces first, and women were more likely to look longer at images of male-on-female sexual acts. The eye-tracking data offers an unexpected explanation for the more intense brain activity in response to visual stimuli men demonstrated in the 2004 study and others like it. Much of the increased activity is centered in the amygdala, which is deeply involved in processing emotion. So the increased brain activity may be the result of all the time men spend looking at faces. Men may be more consciously responsive to visual sexual stimuli than women because they’re more emotional about it. The new vogue of today’s sensitive man may not be so new after all.
By the way, paying for porn is no longer unique to humans. Researchers at Duke University offered male rhesus monkeys the chance to see pictures of female monkey bottoms, but only if they paid for it by giving up their fruit juice. The monkeys paid up.
IMAGINE FOR A second it’s a beautiful spring day, and a woman sees a good-looking man across the aisle at the grocery store—you know…tall, dark, handsome, and symmetrical. She catches his eye, and she gets that familiar tingle. Why does that familiar tingle seem to be so familiar every spring?
Spring fever, of course. It’s directly related to the increased sunlight that follows winter. The explanation for spring fever is actually pretty straightforward. Increased sunlight, which is detected by your eyes and via the optic nerve, and a group of neurons in the brain called the suprachiasmatic nuclei, eventually communicate to the part of the brain known as the pineal gland. The reporting of sunlight prompts your pineal gland to cut down its production of melatonin. Discovered in the late 1950s by a team of Yale researchers led by dermatologist Dr. Aaron B. Lerner, melatonin is a hormone that our body produces naturally which is involved in the regulation of circadian rhythms. This is the cycle of bodily chemistry and behavior that you follow from day to day—the most basic, of course, being awake and asleep. Melatonin has gotten some fair attention as an over-the-counter aid for long flights, supposedly helping people find midair sleep easier and jet lag less of an issue. And naturally occurring melatonin in our bodies is certainly linked to the desire to sleep and changes in mood. So, as we bask in spring’s sunlit glow, we’re also tamping down on the flow of melatonin, waking us up, lifting our mood, and, in many cases, possibly turning us on. Of course, after a long winter, the fact that it’s finally spring doesn’t hurt either.
Back to the guy across the grocery store aisle. She’s now holding his gaze, and tilting her neck to one side. Her mouth is curling in a not terribly subtle hint of a smile. Is he staring right back at her, maybe raising his eyebrows a bit? Yes, they’re flirting.
Flirting is the body language call and response of the mating game, and its vocabulary and grammar are deeply ingrained in our subconscious. “Flirting is a way of testing one’s mate-value and the possibility of alternatives—actually trying to see if someone might be available as an alternative,” says Arthur Aron, a psychology professor at the State University of New York at Stony Brook. When Irenaus Eibl Eibesfeldt filmed African tribes in the 1960s, he found women doing the exact same tilt of the head and little smile we just imagined a woman offering the man in the grocery store. Of course, flirting is not the sole domain of heterosexuals, everyone does it.
You see somebody who looks attractive. You flirt with them. They flirt back. At some point, you’re probably close enough to smell them. You keep flirting. So do they. And whether it’s another ten minutes, or over a series of dates, if you keep responding favorably to each other and things proceed, eventually it happens.
The first kiss. Why do we kiss in the first place? Zoologist and author Desmond Morris proposed in the 1960s that kissing might have evolved from primate behavior termed pre-chewing. This is the practice in which a mother would begin masticating or chewing food (prior to the modern convenience of commercial baby food), before passing it off to her young, using her mouth.
Regardless of how the practice of kissing arose, it is important to mention that it’s not totally cross-cultural. In The Expression of the Emotions in Man and Animals, published in 1898, Charles Darwin wrote in reference to kissing: “It is replaced in various parts of the world, by the rubbing of noses.” This behavior possibly refers to the practice of kunik, historically practiced by the Inuit and somewhat similarly by the Maori; it’s part sniff, part nuzzle, not the commonly mistaken “rubbing of the noses.”
In the majority of cultures where kissing is practiced, it can be a very important test of a relationship’s potential. In fact, a study published in 2007 says the first kiss is so important it can kick a budding relationship into higher gear or cut it off altogether. In the study, 59 percent of the men and 66 percent of the women reported having been initially attracted to someone, but losing interest when the first kiss just didn’t feel right. Why? The study’s author thinks it’s because you’re still playing the mating game—gathering information, making judgments, assessing this person’s suitability as a potential mate and possible partner—and you’ve just raised the stakes. And, when you kiss, you exchange all kinds of information with the person you’re kissing. In an article in Scientific American, author George Gallup of the State University of New York at Albany said:
Kissing involves a very complicated exchange of information—olfactory information, tactile information and postural types of adjustments that may tap into underlying evolved and unconscious mechanisms that enable people to make determinations…about the degree to which they are genetically incompatible.
To put it in the most straightforward terms, if you kiss somebody who tastes unpleasant, it’s likely to turn you off. Which makes me think that the odds are that bad taste means something; it could be a sign of a microbial infection—for example, the bacterium Helicobacter pylori that’s associated with ulcers—or other parasites and even diseases. Or it might just mean all is not right.
For the most part, though, since we’ve made it this far as a species, nature has come to ensure that we enjoy sexual intimacy with others. Next we’re going to find out how the way we look, smell, taste, and act come together in the big payoff: sex.
CHAPTER 4
let’s talk about sex
The experience of having sexual intercourse for the first time really runs the gamut—it can be unbelievably rewarding, utterly indifferent, or even emotionally damaging, depending on a host of factors, beginning with the age, maturity, and the relationship between the partners. But one thing it always is. It’s new. And lots of cultures place enormous value on making sure that it really is new—that the first time is truly the first, especially for young women. In many of those cultures, people believe the only way to tell for sure is to examine the hymen. They believe that an intact hymen is the only true proof of female virginity.
The hymen is found directly at the vaginal opening. Hymens, like every other part of the body come in many different varieties. It’s a mucous membrane that typically covers a portion of the vaginal opening in a circular shape or crescent. It is estimated that one in every one thousand to ten thousand girls are born every year with an imperforate hymen—a hymen that covers the entire vaginal opening. If that doesn’t resolve by puberty, it can prevent the flow of menstruation out of the body. Typically, young teenagers eventually show up at their doctors complaining of monthly pelvic pain and primary amenorrhea, which is the medical term for never having menstruated. An imperforate hymen needs to be opened surgically with a procedure called a hymenotomy, to allow the products of menstruation to flow out of the body. And, on the other end of the spectrum, although most girls are born with hymens, some are not. This can pose a real problem in societies where intact hymens have serious cultural significance. In fact, in some parts of the world being born without a hymen can be downright deadly. Among the Yungar people of Australia, for example, the lack of an intact hymen before marriage in the pa
st, could have resulted in torture, forced starvation, and even death.
Through the ages women came up with some pretty ingenious methods to protect themselves from the consequences of a ruptured or absent hymen. According to Dr. Jelto Drenth, author of The Origin of the World: Science and Fiction of the Vagina, medieval Neapolitan women and nineteenth-century London brothel workers would actually use leeches to ensure a bloody first-night experience and thus convince their men of their virginity. The Trotula, a medieval medical text addressing the health complaints of women, gave the following advice about the use of leeches: “What is better is if the following is done one night before she is married: let her place leeches in the vagina (but take care that they do not go in too far) so that blood comes out and is converted into a little clot. And thus the man will be deceived by the effusion of blood.”
Some women today still go to great lengths to convince their future husbands and in-laws, and even their own family, of their virginity. Sometimes, they even resort to surgery. These feigned virginity procedures can be done right before the wedding and include stitching the vaginal walls together (the stitches don’t go in too deep) to ensure the presence of blood and a little resistance to insertion. Hymenoplasty, a procedure to restore a damaged hymen, is performed in many parts of the world, including Europe, where a growing segment of the population is composed of Muslims, who still place great importance on a bride’s chastity. In many countries such as Turkey, performing a hymenoplasty is risky, both for the doctor and the patient, because there are laws and cultural traditions that punish performing or accepting such procedures. To convince doctors to perform a hymenoplasty without revealing the loss of their virginity, many women contrive stories that strain credulity, like falling on a fence. Even after finding a willing doctor, they still must come up with the money to pay for it. In the United States and Europe the procedure can cost anywhere from $2,000 to $4,000.
The hymen hasn’t always been held in such high regard. Indian courtesans actively sought its removal. According to the Kama Sutra, thought to have been compiled sometime in the third century A.D., “the courtesan gets rid of her daughter’s virginity with the assistance of a female friend or slave, so as to facilitate her amorous success. Once she has thoroughly studied the practice of sexual relations according to the Kama Sutra, she liberates her daughter. Such is the ancient custom.”
For all the importance attached to them, are hymens the great indicators of virginity that they’re thought to be? It turns out that even if hymens do tear, they can heal. And many women do not even have hymens—so if you don’t have an intact hymen to start with, intercourse isn’t going to tear it. It’s also pretty darn easy to tear a hymen through nonsexual activity. Some women who are virgins will have already torn their hymens through some type of physical activity, or even tampon use. And, on top of all that, an intact hymen really isn’t proof that you’re a virgin. The hymen becomes very elastic at puberty, so much so that it can remain intact in many women even after intercourse. A study from the Archives of Pediatric Adolescent Medicine in 2004 found that half of the young women who admitted to having sexual intercourse actually still had intact hymens; in some cases, as hymens elasticize at puberty, they can stretch during intercourse without tearing. Some women have even become pregnant with intact hymens.
The bottom line is simple—a hymen might tear the first time, it might tear long before that, and, barring delivering a baby vaginally, it might not tear at all.
THERE’S PRETTY CLEAR evidence that there are some evolutionary pressures behind promiscuity, especially on the part of men (although men obviously don’t have a monopoly on infidelity). To some degree, this explains why hymens may have been given such importance in so many different cultures. While evolution may have worked to encourage pair bonding and commitment through our chemical response to sex, it’s not Cupid all the time.
Generally speaking, across most animal species, male reproductive success hinges on mass distribution, and female reproductive success depends on careful selection and conservation. Sperm are small, multitudinous, and continually replenished. Eggs are large, precious, and probably not produced after birth. In other words, sperm are cheap and eggs are expensive.
When a male and a female have sex, millions of sperm compete for the chance to fertilize, with very few exceptions, just one egg. And, if a given female has sex with more than one male, then the odds that any one of her individual male partners is going to succeed in reproducing drop accordingly, while hers increase. So, from an evolutionary perspective, the best way for a male to increase his odds of passing his genes on is to distribute his sperm as widely as possible among fertile females, in the hopes that sooner or later one of those sperm will beat the odds and fertilize an egg. Females, on the other hand, have an interest in seeking males who will give her the healthiest offspring so that the huge investment her body makes in pregnancy and child-rearing is worth it. Ultimately, males and females both have an interest in multiple sexual partners, but for different reasons.
And that’s the way it is in most species; they’re polygamous. But a few species—around 5 percent of mammals—are monogamous. More precisely, in scientific terms, they’re known as socially monogamous, because they pair up with an individual of the opposite sex for life, although they are still very likely to mate outside the pair-bond.
In the last few years, scientists studying a furry little rodent called a vole have actually identified a single gene that is responsible for making one variety, the prairie vole, monogamous, while a closely related animal called the montane vole is polygamous.
Scientists have long known that prairie voles mate for life—couples live in the same nest, and males help to care for offspring; males, and sometimes females, may go off and copulate outside the pair-bond, but they always return. Male montane voles, on the other hand, are essentially all about one-night stands—there is no relationship after the mating act itself, even when it results in pregnancy and a litter.
The regulation of oxytocin and vasopressin (a closely related hormone), and their corresponding receptors in certain parts of the brain, is what is thought to turn a vole from frisky to loyal. Why would some voles evolve to be monogamous and others polygamous? Remember that evolution is all about trade-offs. Polygamy lends itself to genetic diversity and increases the likelihood that an individual male will pass his genes on. But monogamy creates a safer environment for offspring, giving them a better chance to survive, reach adulthood, and reproduce themselves, keeping the genetic chain alive. So in a particularly predator-heavy environment, for example, monogamy might give animals a greater advantage.
In that light, it’s easy to imagine how competing pressures—for males to disseminate their sperm widely but also to protect their offspring—might lead to monogamous and polygamous tendencies in the same species.
Fascinating research, published in 2008, by Swedish geneticists has just linked the presence of a single gene that affects the location of vasopressin receptors in human males to the likelihood of marital problems. Remember, it’s not just the existence of vasopressin that affects vole behavior—vasopressin exists in both species of voles; it’s where that vasopressin is sensed, through the presence of their receptors, and processed in the brain. Hasse Walum, a behavioral geneticist at Sweden’s Karolinska Institute, led a study published in the Proceedings of the National Academy of Sciences in 2008 that looked for copies of a gene called RS3 334 in 552 Swedish men who had been in a committed heterosexual relationship for at least five years. The team then interviewed the men and their partners about their relationships. The results were striking:
Men with two copies of the allele [another word for a copy of a gene] had twice the risk of experiencing marital dysfunction, with a threat of divorce during the last year, compared to men carrying one or no copies. Women married to men with one or two copies of the allele scored lower on average on how satisfied they were with the relationship compared to women married to me
n with no copies.
So how prevalent is this gene? Forty percent of all men have at least one copy of it. But that doesn’t mean that 40 percent of all men are going to have problems in their marriages. Genetic tendencies can influence our behavior, but we have the capacity to exercise control over impulses, especially when we understand the possible influences upon us. There are some people who can never imagine themselves staying faithful. They may even join a growing minority of couples opting for “open” marriages, where sex outside of the relationship is accepted. But, for the visible majority that choose the more traditional definition of marriage, knowing the triggers to infidelity can help tip the odds in your favor. As Helen Fisher, a biological anthropologist and the author of Why We Love: The Nature and Chemistry of Romantic Love, noted:
There are many ways this information can help a man and his wife when they marry. Knowing there are biological weak links can help you overcome them. You can say, “Oh, it is just my DNA, and I am going to ignore it.”…Some people will go into marriage with a stronger deck of cards. But there are people genetically prone to alcoholism who give up booze and make a good marriage. No one is saying biology is destiny.
Exactly. But sex is biology (and anatomy, anthropology, chemistry, psychology, and sociology, too). So let’s delve a little deeper into what happens when men and women have sex.
LIKE JUST ABOUT anything else, sex gets better for most people with practice. The goal is good, rewarding sex with your partner, and that usually means one or more orgasms for the both of you.
How Sex Works Page 10