Decoding Love Read online

  CHARLES DARWIN—THE WORLD’S FIRST DATING GURU

  First, a little background on Charles Darwin, who has had a rough go of it in this country. A substantial portion of Americans still don’t believe in evolution, but that’s nothing new for Darwin, who has been fighting an uphill battle for quite some time. He first made the case for evolution in Origin of the Species—his most famous work—in 1859. But we’re interested in a later work of Darwin’s, his 1871 book Descent of Man, which explains one aspect of evolution: sexual selection.

  When we think of Darwin, most of us remember the phrase “the survival of the fittest,” or what is known as natural selection. Darwin’s theory of sexual selection is a subset of that, what you might call “reproduction of the fittest.” To put it in the most basic terms, natural selection has to do with the ability to adapt to the environment, while sexual selection is concerned with how to acquire mates. And it turns out that sexual selection is really the essential element because the key to any animal’s success is not simply his or her ability to survive but also his or her ability to pass along genes to future generations. In other words, you can be the fastest male Kudu around, but if you don’t know how to make it with a female Kudu, you won’t matter from an evolutionary standpoint. If Darwin’s original ideas about evolution were slow to gain acceptance, the speed at which sexual selection gained adherents was glacial.

  If you are willing to take the Darwinian view seriously, I have some good news, some bad news, and one disappointing truth. First, the good news. You are a spectacular evolutionary success story, representing an unbroken chain of thousands of ancestors who managed not just to survive but to attract a sexual partner and successfully rear a child. So, let me be the first to say, kudos to you!

  Now, for the bad news. You are surrounded by people who are every bit as much of an evolutionary success as you are. In fact, you are caught in what biologists have called a Red Queen situation, named for the Red Queen in Lewis Carroll’s Through the Looking Glass, who says to Alice, “It takes all the running you can do to stay in the same place.” And that’s the situation all of us find ourselves in now. You see, no matter how well we adapt to our current environment, our competition and our enemies keep adapting as well. We don’t have to worry too much about our enemies anymore. Very few of us are likely to be eaten by a lion after all, but we have to worry a great deal about our competition, i.e., other humans, billions strong and growing more numerous every day.

  And now for the disappointing truth. Dating—the whole effort to find a lifetime partner with whom to mate—doesn’t just seem hard. It is hard. And it’s supposed to be hard. That’s the necessary outgrowth of a Red Queen situation. Do you ever watch television shows from the 1950s or even the 1980s and find that they seem slow, that the dialogue and plot are crude, the characters shallow and obvious? That’s a cultural example of the kind of Red Queen situation I’m discussing. You’ve come to expect faster pacing and more complex characters. In short, you’ve become a much more sophisticated consumer of television shows than the previous generation. The problem is that everyone else has become more sophisticated as well, so your growth in understanding doesn’t provide a competitive advantage. It only helps you keep pace with the pack. Now, imagine the same scenario for dating. All your hard work in terms of looking good and developing an interesting personality only serves to hold your place. That’s why it seems so difficult. The romantic story line blinds us to that fact by serving up the fantasy that finding the right person is as easy as slipping your foot into a glass slipper.

  I have an added piece of good news. If you accept Darwin’s ideas about sexual selection, then the animal kingdom can shed quite a bit of light on the nature of human relationships. Before I turn to the world of animals, though, I want to add one caveat. I will be discussing biological tendencies, but that is not the same thing as offering moral justifications. For example, just because men have an evolutionary tendency to commit adultery, that does not mean adultery is okay. We are not slaves to our biological urges. We are also products of cultures that establish certain moral and legal codes. But we’ll get to cultural explanations in the next chapter.

  CHIMPS OR BONOBOS?

  So, let’s look at man the animal. Our closest relatives are the chimpanzee and the bonobo. The first hominid (not yet a homo sapien but of the same genus) diverged from them roughly six to seven million years ago, which is far more recent than the fifteen to twenty million years biologists once thought separated us. This is actually a very short time in evolutionary terms. At the molecular level, there is only about a 1 percent difference between humans and chimpanzees. We are closer to the chimpanzee than the chimpanzee is to the orangutan, and chimps are not only our closest relative—we are their closest relative as well.

  Over the years, biologists have claimed any number of differences between us and primates, only to see them fall by the way-side. The latest—and one of the most sophisticated—is the claim that humans are the only ones to have a theory of mind (the ability to imagine what other people are thinking), but recent experiments have revealed even that order of higher-level thinking to be something that chimpanzees exhibit.

  Of course, if we accept that chimps and bonobos are our closest relatives, we are left with one absolutely essential question: are we more like chimps or bonobos? The question carries larger implications than you may realize. Just take the matter of sex. With chimpanzees, power is used to resolve questions about sex. With bonobos, though, sex is used to resolve questions of power. Needless to say, this leads to two very different social orders. With chimpanzees, males dominate, and there is a very strict hierarchy. Alliances are constantly forming and re-forming to try to topple the dominant male chimpanzee who has extensive, although not exclusive, control of sexual access to the females. There is a great deal of posturing and even violence, and it is not uncommon for chimpanzees to kill one another. Think of how violent gangs act in prison, and you have a rough human approximation of a chimpanzee society.

  But bonobos are like bizarro chimps. Their social order flips everything on its head. In a bonobo troop, the females dominate. Consequently, male aggression is greatly reduced. And because the males do not have to jockey with one another for sexual access, the males spend a lot less time trying to rise in the hierarchy. If there is a dispute, bonobos generally resolve it using sex and engage in an incredibly diverse array of sexual practices. Picture the most freewheeling sexual commune from the late sixties in America, and you probably have the closest approximation to bonobo society in this country’s history. Talk about giving peace a chance! As primatologist Frans de Waal has aptly put it, we are left with a choice between the power hungry and brutal chimp or the peace-loving and erotic bonobo.

  This has implications not just for our sex lives but for our political lives as well. According to de Waal, primate evolution suggests that rigid hierarchies came first and that equality only developed much later. Monkeys display a rigid hierarchy, and chimpanzees are somewhere in between monkeys and our own attempts at equality. Lest we think that we Americans have long thrown off any vestiges of a rigidly stratified past, our own voices betray our less egalitarian roots. Below 500 hertz, the voice produces meaningless noise. If you filter out the high-pitched noise, you will hear only a low hum. But it turns out that this noise is a hidden window into the unconscious way we are always monitoring our status within a group. During a conversation between two people, the two voices tend to converge, but the amazing part is that the lower-status person is always the one who makes the largest adjustment toward the pitch of the higher-status person. In a study of guests on Larry King, Dan Quayle made the most obvious adjustment of any of King’s guests, which should give us some sympathy for the hapless former vice president. Although we are the most sophisticated animals when it comes to communication, with a vast and complicated language, words blind us to these other levels of communication, so much so that a number of studies have shown that animals can bett
er intuit our moods than we can ourselves.

  Unfortunately, there is no clear-cut answer about whether humans are more like chimps or bonobos, although recent times provide far more examples of societies organized around violence and hierarchy than they do of societies organized around freewheeling sex. But perhaps the most crucial element of comparison is a key difference. Despite all of our similarities, we diverge from chimps and bonobos in one absolutely essential respect—we are the only ones to form long-term pair bonds. And that difference has enormous ramifications.

  WHY WE GAVE UP PARTNER SWAPPING FOR STABILITY

  The question is, why? What force caused this behavior in human beings? The answer is quite simple: children. Our babies are born in an almost absurdly helpless condition and remain that way for a long time. Based on studies of modern hunter-gatherer societies (which roughly approximate our original evolutionary environment), children aren’t able to produce as much food as they eat until they are about fifteen years old. So, pair-bonding was likely a biological necessity. If women were left to raise the children completely on their own with no help from the father, many fewer children would have survived until adulthood—a far more ruthless calculus than what we find in the romantic story line and one that continues to have more relevance today than we care to admit. Have you ever wondered why evil stepparents are so often at the center of children’s fairy tales? It turns out that there is a good reason for this widespread cultural anxiety—a stepchild is sixty-five times more likely to be fatally abused than a child living with his or her biological parents.

  But pair-bonding didn’t just happen overnight. Humans had to evolve in a manner that reinforced the pair-bond, which they did in a number ways. Let’s start with sex. The first question is, why even have sex? From a genetic standpoint, it is inefficient, since only 50 percent of your genes are passed to your child. There are plenty of other methods of reproduction—some of them positively mind-boggling—that have evolved in the natural world: multisexual for the swingers out there, female only for the feminists, bisexual for the indecisive, asexual for the squeamish, parthenogenesis (virgin birth) for the Christian, and even a few species in which the sex of an individual animal can change back and forth for the transgendered. We could easily pass along our genes far more effectively if we had gone down the path of asexual reproduction, for example. The problem is that this would have left us vulnerable to parasites, which evolve much faster than we do. How much faster? It took millions of years and roughly 250,000 generations for us to split from chimpanzees and become homo sapiens. For E. coli bacteria to experience a similar number of generations would take only nine years. So, sex was the method humans and other animals evolved to fight back against parasites. Simply put, sex allows for far more genetic variation and helps keep us from succumbing to our various bacterial and viral invaders—another classic Red Queen situation in which our evolving immune systems are working hard, simply not to fall behind the parasites attacking us.

  When it comes to sex, men and women can congratulate themselves on being the great endurance athletes of the primate world. No, we can’t match chimpanzees or bonobos or many other species in the frequency of our sexual encounters, but we blow away virtually every other primate when it comes to the duration of our coitus. Pygmy chimps clock in at a lightning-fast fifteen seconds, which seems unbelievably short until you consider the common chimpanzee, which manages to get the job done in only seven seconds (although this does not mean that female chimps aren’t enjoying themselves. According to one study, female chimps can have an orgasm after only twenty or so thrusts). This is roughly on par with baboons, who take about fifteen pelvic thrusts. Gorillas come in at a leisurely one minute. Meanwhile, the average American couple has barely begun, averaging a full four minutes. We are bested only by the orangutan, which averages about fifteen minutes for copulation, but we’ll leave them to one side since they are obviously busy getting it on with one another.

  As always when you find this sort of discrepancy in behavior, evolutionary thinking demands an explanation, particularly when there is an obvious downside to increasing the length of copulation. First, during the act, you are vulnerable to attack, and second, the longer you have sex, the more precious energy you are using. The answer lies in the pair-bond. It turns out that sex in humans is much more about developing a bond than it is about procreation. Not that procreation isn’t essential. Obviously, that’s what all this is about at the end of the day. But that is just an occasional by-product. In fact, if you looked at human sex from the standpoint of efficiency, it’s a disaster. Even during their most fertile years, many couples can take months to conceive.

  Once you look at sexual activity primarily as a way to strengthen the pair-bond, though, you can begin to make sense of a variety of oddities about human beings. For instance, women have a tipped vagina, which promotes more intimate face-to-face copulation, and large breasts, which are on permanent display and act as a constant advertisement of sexual receptivity totally disconnected from ovulation. In contrast, most female mammals only develop enlarged breasts when they are pregnant. Ethologist Desmond Morris argues that various other features—fleshy earlobes, protruding noses, and everted lips—are also designed to promote face-to-face copulation. Even the loss of body hair was possibly a means of promoting the pair-bond.

  Perhaps most important, women developed concealed ovulation, which makes it impossible for men to tell when it’s the ideal time to mate. This makes her distinct among primate females, all of which have visible displays of their fertility (think of certain primates in which the females buttocks turn bright red during estrus). Further confounding male efforts to determine the time of peak fertility, women do not limit their sexual activity to the time they are ovulating. These developments likely played a crucial role in cementing her bond with a man. Instead of guarding a woman jealously for a few days during ovulation, the man had to develop a long-term relationship to try to ensure that her offspring would also be his. Anthropologist Helen Fisher has called this the “sex contract” that evolved to secure women the help they needed to raise their children.

  CHEAP SPERM AND PRECIOUS EGGS

  So, with all of these traits to promote pair-bonds, everything should be great when it comes to the relationship between a man and a woman, right? Unfortunately, no. To understand why, we need to explore the crucial role of two largely unmentioned participants in all of this pair-bonding, the sperm and the egg. It is at their fruitful conjunction that everything happens. But what they do to get there and how their carriers (i.e., men and women) feel about that journey makes all the difference.

  It took a while for scientists to realize the significance of this. Although they were busy studying and refining Darwin’s arguments, sexual selection didn’t receive a lot of attention, particularly when it came to one particular segment of the animal kingdom—human beings. While happy to study the mating rituals of everything from slugs to lemurs, scientists proved reluctant to put humans under the microscope, albeit with a few high-profile exceptions such as Alfred Kinsey. That all began to change in 1972 when Robert Trivers published an essay entitled “Parental investment and sexual selection.” Despite the rather pedestrian title, that essay is possibly the single-most influential piece of evolutionary theory to come along since Darwin’s original concept of sexual selection. What Trivers discovered was no less than the key to sexual selection, the engine, as it were, that made the whole thing run. That engine was parental investment.

  Trivers’s revolutionary insight was simple. The investment a parent makes in his or her offspring has a huge influence on how that parent will approach mating. The more investment a parent makes, the more selective that parent will be in choosing a mate. The less investment a parent makes, the more sexual competition there will be to attract a mate. Think of the many men who often crowd around an attractive woman at a bar, and you have a pretty good picture of this dynamic at work. Which brings us back to the sperm and the egg. You
see, sperm are cheap. The average man’s ejaculate contains hundreds of millions of the little buggers (over his lifetime, he will produce two trillion). And although he has nowhere near the sexual ardor of a ram or even a chimpanzee, a young, healthy man can have sex several times a day. On top of all that, if the man is more interested in being a cad than a dad, he can walk away after planting his seed and never lift another finger, so his parental investment is potentially miniscule.

  If a man could have sex with an unlimited number of women and conceive with all of them, he could theoretically father hundreds of children in one year, and some famous historical figures have indefatigably attempted to do just that. According to historical records, Moulay Ismael the Bloodthirsty, the emperor of Morocco from 1672 to 1727, fathered 888 children. Recent DNA evidence suggests that Genghis Khan might have fathered an even larger number, and according to research, a mere nineteen male lineages have played the dominant role in populating the world, a remarkable example of the multiplying power of sexual selection for successful males.

  Now, consider the woman and her egg, which is a very precious commodity indeed. A woman ovulates once a month, and once she is pregnant, she must carry that child inside of her for nine months. Even after she has the baby, she will have to care for it, and she is unlikely to get pregnant again right away because breast-feeding makes it more difficult to conceive. Over the course of her lifetime, the typical woman will have approximately four hundred to five hundred ovulations. Compare that to the trillions of sperm men will produce over the course of their lifetime (of course, the egg is 85,000 times larger than an individual sperm). Let’s assume that she manages to have one baby a year during all of her fertile years. It’s possible she could crack twenty. The record is an astounding sixty-nine, which an eighteenth-century Russian achieved by repeatedly having twins (although this figure is possibly apocryphal). Even that extreme number—any woman who has been pregnant will shudder at the thought—pales in comparison to the number of children a man can father, even if he isn’t Ismael the Bloodthirsty. If you are still unconvinced, anthropological evidence also confirms that cheap sperm-precious egg distinction. Seventy percent of human societies involve a payment between the two families. Any guesses as to what percentage of those require a payment to the bride’s family? Ninety-six percent!