Decoding Love Read online

  Ah, but the woman has her own genetic desires. She wants to find a good provider who will help her raise her children, but she also wants the best genes possible. And the two go together far less than you might think. A woman might only be able to get a man of middling rank to marry her, but if she is willing to have a one-night stand with no strings attached, she will be able to have sex with a much more attractive, successful man. By cheating on her husband, the woman can have her cake and eat it, too—she gets a husband who is a good provider and also gets the best possible genes for her child.

  BATTLE OF THE SEXUAL GAMETES?

  I know this sounds far-fetched. Women don’t cheat on their husbands with the express thought of getting their hands on better genetic code. Remember, though, that much of what we are talking about in this chapter occurs below the level of conscious thought. The skeptical among you might use this as a chance to dismiss what I’m saying, but you don’t have to take my word for it. You simply have to look at the human body itself. And what does it show? A constantly evolving arms race between men and women—only in this case the battle is waged not by us but by our proxies, our sperm and our eggs. What we have is a classic Red Queen contest where each side wants to gain an advantage. The man would like to impregnate every woman he sleeps with, while the woman would like to be able to choose who fathers her child. She might find a man who is good enough to marry but still want top-notch sperm from someone on the side. If what I’m saying is true, you would expect both men and women to develop measures to increase their chances. We’ve already seen one very successful strategy of women to thwart a man’s ability to police her fertility: concealed ovulation. But it doesn’t stop with concealed ovulation. Both men and women have developed a host of subtle and shocking measures to increase their chances of genetic success. These measures are both a sign of how deeply we have been shaped by sexual selection and also a disturbing indication of how we are unwitting pawns in a largely invisible genetic struggle. In short, we are a long way from the romantic story line now.

  The clearest evidence of this battle comes from an ingenious study of the fruit fly, published by William Rice in 1996. What Rice did was allow male fruit flies—but not the females they were breeding with—to evolve for forty-one generations. This was a boon for the males. They gradually developed much more effective sperm so that when they mated with a female who had already mated with another of Rice’s evolved males, they were much more likely to impregnate her. The reason for their success? Much more toxic sperm, which basically killed off the rival sperm. That trait came with a cost, though, and the cost reveals quite clearly that sexual evolution is not a matter of both sexes cooperating—it’s usually a case of one sex developing a quality that is actually antagonistic to the other sex. Just how antagonistic? The sperm had grown so toxic that if a female fruit fly had sex with enough of these evolved males, the sperm had a good chance of killing her—talk about a toxic bachelor! Luckily, human sperm remain far from lethal, but an equally fierce competition is being waged every day between our sperm and our eggs.

  So, let’s wade right in and start with one of the more controversial aspects of human sexuality—female orgasm. There is still a fairly vigorous debate about whether or not there is any point to a female orgasm. Although feminists might feel that this is some sort of chauvinistic joke masquerading as science, the subject of female orgasm is a serious issue. The reason for a male orgasm is obvious—the release of sperm. And that also helps explain the almost clocklike regularity of male orgasm (as well as the tendency of some men to ejaculate prematurely—there are many positive benefits to the man coming as quickly as possible, and the downside is borne by women). But women ovulate once a month and can be impregnated without any orgasm, leaving scientists to ponder why a woman needs to have an orgasm at all.

  Although by no means settled, there is one school of thought I find persuasive. It appears that female orgasm might function as a highly sensitive sexual selection device—and one that sticks a dagger into the heart of the romantic story line. Researchers conducted a study of when women had orgasms. The surprising finding was that the level of a woman’s romantic attachment did not increase the frequency of her orgasm, nor did it depend on the man’s sexual skill. That’s right. Despite hundreds of books on how to be a better lover, women’s orgasms have little to do with a man’s abilities or even the love the woman has for a man. What did increase the likelihood of female orgasm? How symmetrical a woman’s partner was—in other words, how much a man’s left and right sides mirrored each other. I know that sounds preposterous, but symmetricality is actually a pretty good indicator of health, i.e., genetic fitness. The more disease and illness, the less symmetrical someone tends to be (studies have also found that less symmetrical men tend to have lower IQs). Think Quasimodo, and you will have an extreme version of someone who is asymmetrical. And researchers have found that women orgasm more with symmetrical men. Simply put, female orgasms appear to be largely predicated on a subconscious evaluation of a man’s genetic merit.

  So what does all that have to do with the orgasm as a sexual selection device? Robin Baker and Mark Ellis studied whether or not a woman’s orgasm had an effect on the amount of sperm her body retained, and what they found was that a woman’s orgasm has an enormous effect. If a woman doesn’t orgasm or has an orgasm more than a minute before the man ejaculates, she retains very little of the sperm. But if she has an orgasm less than a minute before he does or up to forty-five minutes afterward, she retains most of the sperm, which vastly increases the chances that her egg will be fertilized (they measured the “flowback”—the amount of ejaculate discharged from the vagina shortly after sex—from more than three hundred copulations, by having the women squat over a beaker). So, a man who can make a woman orgasm (i.e., a symmetrical man) has a much better chance of impregnating a woman. Scientists call this sort of hidden mechanism that helps a woman’s body choose sperm from a particular male “cryptic female choice.”

  All of this takes an even more disturbing turn when you bring infidelity into the equation. Remember the theory that wives are unfaithful in order to go after genetically superior sperm? It appears that the female orgasm may be actively aiding in this strategy. Another study revealed that wives who were having affairs tended to have adulterous sex at their most fertile times and that 70 percent of those copulations resulted in an orgasm (as opposed to only 40 percent of the copulations with their husbands). In other words, not only were unfaithful wives more likely to have sex with their lovers during their most fertile period, they were also more likely to orgasm and to retain a larger amount of sperm. When the researchers did the math, they discovered that a wife could have sex twice as often with her husband as with her lover but still be more likely to conceive with her lover (studies have also shown that women with regular partners fake orgasms more often, likely as a way of diverting suspicion about their fidelity).

  How likely is it that this sort of hidden sexual selection occurs? A lot more likely than any of us would like to believe. In one study, researchers estimated that 4-12 percent of children born in Great Britain were conceived in an environment of sperm competition, which basically means that sperm from multiple men were in the woman’s vaginal tract at the same time and competing to fertilize the same egg. The same study suggested that the majority of men and women in Western societies have at one time or another engaged in sperm competition. Another recent survey found that one in eight female respondents had sex with two or more men in a twenty-four period.

  Appalling as this method of “cryptic female choice” may be from a man’s point of view, it makes perfect sense from the woman’s point of view. Studies have shown that symmetrical men cheat more often, so the woman is better off going after good genes from the symmetrical man but finding a good provider somewhere else. What all this means is that, far from being some useless evolutionary by-product, the female orgasm is quite possibly a remarkably sophisticated mechanism for the select
ion of superior sperm.

  There are even a few researchers who have proposed the controversial theory that a man’s sperm are designed to war with other sperm. According to this view, fewer than 1 percent of a man’s sperm are designed to fertilize the egg. The rest are a kind of army used to prevent another man’s sperm from fertilizing the egg. Most now consider this idea far-fetched, but it is safe to say that sperm and eggs are locked in an evolutionary arms race and will likely remain that way indefinitely.

  Males are not defenseless in this high-stakes genetic game. One strategy they have evolved is virtually relentless copulation to ensure paternity. Some mammals have even developed copulatory plugs—their ejaculate contains a substance that literally blocks the sperm of rival males. While human males don’t have anything quite so medieval sounding, they have their own “weapons.” One recent study has theorized that the ridged glans on a man’s penis is designed to scoop out a competitor’s semen, and the last part of a man’s ejaculate contains a natural spermicide, a kind of before-and-after protection system against female promiscuity. Researchers have also done a study comparing the ejaculates of men who spent 100 percent of their time with their wives with men who spent less than 5 percent of their time with their wives. The result? Men who have been absent ejaculate with almost twice as much sperm—712 million versus only 389 million. Also, human semen contains prostaglandin, a hormone that can cause uterine contractions and thus undermine the selectivity of the female orgasm. This suggests that men also have some very finely honed evolutionary devices to try to ensure the paternity of their offspring.

  Even on the level of genetic code, men and women are locked in conflict, as Matt Ridley has shown in his fascinating book Genome. At some point in the past, humans switched from the reptilian method of determining sex by the temperature of the egg to a genetic method, which allowed for specialized sex genes to develop. But this is a volatile situation because what is good for one gene can be bad for another gene. For example, the ability to seduce is a great gene for a Y chromosome, but the ability to resist seduction is good for the X chromosome. If one chromosome could strip a quality from another chromosome, that would be a huge advantage for one sex. The problem is that the genetic battle between X and Y is not really a fair fight, because the X chromosome can dominate the Y chromosome. Women have an XX chromosome, and men have an XY. For every one chance a Y chromosome has at undermining something in the X chromosome, the X chromosome has three shots to do the same thing. In this instance, the sexual arms race is a slaughter, and the Y chromosome has done the only sensible thing—run away and hide. To do that effectively, it has become small, very small. While the X chromosome has more than one thousand active genes, the Y chromosome has only twenty-five. Over time, it has basically shut down all but a few essential ones. This gives the X chromosome very few targets to go after and helps make sure that the genetic arms race doesn’t end in complete surrender. Little did you know that the struggle to find Mr. or Ms. Right was being fought even on the genetic level of individual chromosomes, and that a woman’s X and a man’s Y are busy trying to stick it to each other.

  DATING AND DECEPTION

  Given this ceaseless battle on both the human and genetic level, relationships are rampant breeding grounds for deception. Part of the problem is that modern society provides far more opportunities to lie. In our ancestral environment, social groups were smaller, and those who lied would gain a reputation for dishonesty. But in today’s environment, especially in cities or other highly populated areas, there is a much smaller chance of being caught. Internet dating has only increased the problem. Not surprisingly, men and women in relationships lie to each other all the time. In a 1990 study of college students, researchers found that 85 percent of the participants had lied to a partner about a past relationship or an indiscretion. Another study revealed that dating couples lied to each other in about one-third of their interactions. The numbers do improve for married couples, who lied in only 10 percent of their conversations, although the survey found that married couples saved their biggest lies for their partners. Your spouse is probably telling the truth about whether or not she likes your new tie but is possibly lying about whether or not she slept with the mailman. While men are more dishonest than women, they are at least more honest about their dishonesty, giving more accurate estimates of how much they lie than women do. And those are just the lies that we openly acknowledge. The most successful lies are those that we do not even know we are telling, and studies have shown that we are quite good at lying to ourselves about many things having to do with mating, such as how committed we think we are to someone when we are trying to get him or her into bed.

  The deception occurs along predictable lines. Given a culture that frowns on female promiscuity—a man’s greatest fear in any relationship revolves around questions of fidelity and paternity—women quite commonly lie about their sex lives. This helps explain why sexual surveys always show a gross disparity between the number of partners men and women have had (the other cause is that men exaggerate the number of their partners). Researchers found that if they hooked female college students up to a fake lie detector and then asked them about the number of sexual partners they had, women suddenly reported almost twice as many as the women who were not hooked up to the bogus lie detector. For men, there is a quick and easy way to try to get a sense of a woman’s fidelity—if they can get her to divulge her sexual fantasies. One researcher has found that women who have more sexual fantasies about other men are also more likely to be unfaithful. Women also tend to lie about their bodily appearance, although they probably prefer to consider things like padded bras and control-top panty hose enhancements, rather than outright deceptions.

  Women I interviewed frequently admitted that they did not tell men the truth about their sexual pasts. To give one example, an attractive woman in her late twenties was incredibly self-confident about her sexuality and had no problem sleeping with a man for her own pleasure and then never seeing him again. She had already racked up more than thirty partners, and she used to proclaim that fact proudly to the men she was dating—until she realized that they couldn’t handle the information. Some immediately freaked out. Others went off to sulk. In almost every case, it hurt the relationship and sometimes even ended it. Now when she is asked, she always answers that she has slept with six men, which seems to strike the perfect balance between being a prude and being a slut. Another woman said that men she had dated were often afraid to ask because they didn’t want to break the illusion that she had never been with other men, which was an illusion she was happy to allow them to cling to.

  While men’s greatest concerns center on a woman’s potential promiscuity, women get more angry when a man has lied about his income or status or when he has exaggerated his feelings in order to have sex, and studies confirm that men lie more about their resources and their level of commitment as well as how kind, sincere, and trustworthy they are. Needless to say, nearly every woman I interviewed had experienced some form of this. One woman later found that her boyfriend had lied to her about virtually every aspect of his life—his age, his family, his previous jobs. The only thing he didn’t lie about was his current job, and that was only because they worked together.

  What makes deception an even bigger problem is that it turns out that, while seemingly all of us are reasonably adept at lying, we are terrible at telling when other people are lying to us. According to research, people can only distinguish truth from lies 54 percent of the time, which is not much better than random guessing. We’re even worse at picking out lies, which we only manage to achieve 47 percent of the time. Sometimes even the person who is lying isn’t aware that he or she is doing so, which makes detecting the lie nearly impossible.

  Men are so quick to lie in order to have sex that evolutionary psychologist Glenn Geher advises women that if they can’t judge a man’s intention with at least 90 percent accuracy, they are better off being skeptical all the time. Women
should also be more careful prior to entering a relationship. Once they are in a relationship, studies show that they tend to shut off their skepticism and become more vulnerable to deception. If you want to take a more active approach, you can try to train yourself to become better at figuring out when someone is lying, in which case you could turn to Paul Ekman, an expert on facial expressions. He has devoted a substantial part of his professional life to figuring out how to “read” deception in the face of other people and has found that our faces are constantly leaking information about what we are feeling. For example, if your boss makes an annoying request, you might cover up your feeling with a polite smile and a nod of assent, but there was likely a split second (less than a fifth of a second to be more precise) when your face sent a very different message, albeit too fleeting for your boss or even you to notice. Ekman calls these brief moments microexpressions, and with training, you can become better at noticing these facial “leaks.”

  Deception, genetic warfare, measures, and countermeasures—we are a long way from the romantic story line. Although evolutionary psychology offers a great deal of insight into human mating and dating, it is not a pretty picture. Luckily, that is not the end of the story.

  2 ½

  The Dating Animal, Part II

  How Dating Is What Makes Us Human or Darwin Reconsidered

  BEFORE WE BECOME TOO DISHEARTENED ABOUT THE level of deception between men and women, we need to consider the role of deception in the development of the human mind. The old saying is that to err is human, but a more accurate statement might be to lie is human because it appears that social manipulation is at the core of how we became who we are. According to one study, people lie in about 25 percent of their regular daily interactions, which means that even the simplest of human exchanges often involve deception. Take, for example, the smile. Ekman is probably the leading expert in the world at decoding what our faces are actually expressing. What he has found about our smiles is nothing to smile at. He has uncovered nineteen different kinds of smile. How many of those are genuine expressions of pleasure or happiness? One! That’s right. We have nineteen different ways to smile, and only one of them is a truly sincere expression of how we feel.