Incognito (16 page)

What does this research tell us? It tells us that fiscally concerned strippers should eschew contraception and double up their shifts just before ovulation. More importantly, it drives home the point that the beauty of the maiden (or man) is neurally preordained. We have no conscious access to the programs, and can tease them out only with careful studies. Note that brains are quite good at detecting the subtle cues involved. Returning to the most beautiful person you know, imagine that you measured the distance between his or her eyes, as well as nose length, lip thickness, chin shape, and so on. If you compared these measurements to those of a not-so-attractive person, you would find that the differences are subtle.
To a space alien or a German Shepherd dog, the two humans would be indistinguishable, just as attractive and unattractive space aliens and German Shepherd dogs are difficult for you to tell apart. But the small differences within your own species have a great deal of effect in your brain. As an example, some people find the sight of a woman in short shorts intoxicating and a male in short shorts repulsive, even though the two scenes are hardly different from a geometrical perspective. Our ability to make subtle distinctions is exquisitely fine-grained; our brains are engineered to accomplish the clear-cut tasks of mate selection and pursuit. All of it rides under the surface of conscious awareness—we get to simply enjoy the lovely feelings that bubble up.

Beauty judgments are not only constructed by your visual system but are influenced by
smell as well. Odor carries a great deal of information, including information about a potential mate’s age, sex, fertility, identity, emotions, and health. The information is carried by a flotilla of drifting molecules. In many animal species, these compounds drive behavior almost entirely; in humans, the information often flies beneath the radar of conscious perception, but nonetheless influences our behavior.

Imagine we give a female mouse a selection of males to mate with. Her choice, far from being random, will be based on the interplay between her
genetics and the genetics of her suitors. But how does she have access to that kind of hidden information? All mammals have a set of genes known as the major histocompatibility complex, or MHC; these genes are key players in our immune systems. Given a choice, the mouse will choose a mate with
dissimilar
MHC genes. Mixing up the gene pool is almost always a good idea in biology: it keeps genetic defects to a minimum and leads to a healthy interplay of genes known as hybrid vigor. So finding genetically distant partners is useful. But how do mice, who are largely blind, pull this off? With their noses. An organ inside
their noses picks up pheromones, floating chemicals that carry signals through the air—signals about things such as alarm, food trails, sexual readiness, and, in this case, genetic similarity or difference.

Do humans sense and respond to pheromones the way mice do? No one knows for sure, but recent work has found receptors in the lining of the human nose just like those used in pheromonal signaling in mice.
³²
It’s not clear if our receptors are functional, but the behavioral research is suggestive.
³³
In a study at the University of Bern, researchers measured and quantified the MHCs of a group of male and female students.
³⁴
The males were then given cotton T-shirts to wear, so that their daily sweat soaked into the fabric. Later, back in the laboratory, females plunged their noses into the armpits of these T-shirts and picked which body odor they preferred. The result? Exactly like the mice, they preferred the males with more dissimilar MHCs. Apparently our noses are also influencing our choices, again flying the reproduction mission under the radar of consciousness.

Beyond reproduction, human pheromones may also carry invisible signals in other situations. For example, newborns preferentially move toward pads that have been rubbed on their mother’s breast rather than clean pads, presumably based on pheromonal cues.
³⁵
And the length of women’s menstrual cycles may change after they sniff the armpit sweat of another woman.
³⁶

Although pheromones clearly carry signals, the degree to which they influence human behavior is unknown. Our cognition is so multilayered that these cues have been reduced to bit players. Whatever other role they have, pheromones serve to remind us that the brain continuously evolves: these molecules unmask the presence of outdated legacy software.

Consider your
attachment to your mother, and the good fortune of her attachment back to you—especially when you needed her
as a helpless infant. That sort of bonding is easy enough to imagine as a natural occurrence. But we need merely to scratch the surface to find that social attachment relies on a sophisticated system of chemical signaling. It doesn’t happen by default; it happens on purpose. When mice pups are genetically engineered to lack a particular type of receptor in the opioid system (which is involved in pain suppression and reward), they stop caring about separation from their mothers.
³⁷
They let out fewer cries. This is not to say that they are unable to care about things in general—in fact, they are more reactive than normal mice to a threatening male mouse or to cold temperatures. It’s simply that they don’t seem to bond to their mothers. When they are given a choice between
smells from their mother and smells from an unknown mouse, they are just as likely to choose either one. The same thing happens when they are presented with their mother’s nest versus a stranger’s nest. In other words, pups must be running the proper genetic programs to correctly care about their mothers. This sort of problem may underlie disorders that involve difficulties with attachment, such as autism.

Related to the issue of parental bonding is that of staying faithful to one’s partner. Common sense would tell us that monogamy is a decision based on moral character, right? But this leads to the question of what constitutes “character” in the first place. Could this, too, be guided by mechanisms below the radar of consciousness?

Consider the prairie vole. These little creatures dig through shallow underground runways and stay active all year. But unlike other voles and other mammals more generally, prairie voles remain monogamous. They form life-long pair bonds in which they nest together, huddle up, groom, and raise the pups as a team. Why do they show this behavior of committed affiliation while their close cousins are more wanton? The answer pivots on
hormones.

When a male vole repeatedly mates with a female, a hormone called
vasopressin is released in his brain. The vasopressin binds to receptors in a part of the brain called the nucleus accumbens,
and the binding mediates a pleasurable feeling that becomes associated with that female. This locks in the monogamy, which is known as pair-bonding. If you block this hormone, the pair-bonding goes away. Amazingly, when researchers crank up the levels of vasopressin with genetic techniques, they can shift polygamous species to monogamous behavior.
³⁸

Does vasopressin matter for human relationships? In 2008, a research team at the Karolinska Institute in Sweden examined the gene for the vasopressin receptor in 552 men in long-term heterosexual relationships.
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The researchers found that a section of the gene called RS3 334 can come in variable numbers: a man might carry no copies of this section, one copy, or two copies. The more copies, the weaker the effect that vasopressin in the bloodstream would have in the brain. The results were surprising in their simplicity. The number of copies correlated with the men’s pair-bonding behavior. Men with more copies of RS3 334 scored worse on measures of pair-bonding—including measures of the strength of their relationships, perceived marital problems, and marital quality as perceived by their spouses. Those with two copies were more likely to be unmarried, and if they were married, they were more likely to have marital troubles.

This is not to say that choices and environment don’t matter—they do. But it
is
to say that we come into the world with different dispositions. Some men may be genetically inclined to have and hold a single partner, while some may not. In the near future, young women who stay current with the scientific literature may demand genetic tests of their boyfriends to assess how likely they are to make faithful husbands.

Recently, evolutionary psychologists have turned their sights on love and divorce. It didn’t take them long to notice that when people fall in love, there’s a period of up to three years during which the zeal and infatuation ride at a peak. The internal signals in the body and brain are literally a love drug. And then it begins to decline. From this perspective, we are preprogrammed to lose interest in a sexual partner after the time required to raise a
child has passed—which is, on average, about four years.
⁴⁰
The psychologist
Helen Fisher suggests that we are programmed the same way as foxes, who pair-bond for a breeding season, stick around just long enough to raise the offspring, and then split. By researching divorce in nearly sixty countries, Fisher has found that divorce peaks at about four years into a marriage, consistent with her hypothesis.
⁴¹
In her view, the internally generated love drug is simply an efficient mechanism to get men and women to stick together long enough to increase the survival likelihood of their young. Two parents are better than one for survival purposes, and the way to provide that safety is to coax them into staying together.

In the same vein, the large eyes and round faces of babies look cute to us not because they possess a natural “cuteness” but because of the evolutionary importance of adults taking care of babies. Those genetic lines that did not find their infants cute no longer exist, because their young were not properly cared for. But survivors like us, whose mental umwelt cannot let us
not
find babies cute, successfully raise babies to compose the next generation.

We’ve seen in this chapter that our deepest instincts, as well as the kinds of thoughts we have and even
can
have, are burned into the machinery at a very low level. “This is great news,” you might think. “My brain is doing all the right things to survive, and I don’t even have to think about them!” True, that is great news. The unexpected part of the news is that the conscious
you
is the smallest bit-player in the brain. It is something like a young monarch who inherits the throne and takes credit for the glory of the country—without ever being aware of the millions of workers who keep the place running.

We’ll need some bravery to start considering the limitations of our mental landscape. Returning to the movie
The Truman Show
, at one point an anonymous woman on the telephone suggests to
the producer that poor Truman, unwittingly on TV in front of an audience of millions, is less a performer than a prisoner. The producer calmly replies:

As we begin to explore the stage we’re on, we find that there is quite a bit beyond our umwelt. The search is a slow, gradual one, but it engenders a deep sense of awe at the size of the wider production studio.

We’re now ready to move one level deeper into the brain, uncovering another layer of secrets about what we’ve been blithely referring to as
you
, as though you were a single entity.

On July 28, 2006, the actor Mel Gibson was pulled over for speeding at nearly twice the posted speed limit on the Pacific Coast Highway in Malibu, California. The police officer, James Mee, administered a breathalyzer test, which revealed Gibson’s blood
alcohol level to be 0.12 percent, well over the legal limit. On the seat next to Gibson sat an open bottle of tequila. The officer announced to Gibson that he was under arrest and asked him to get into the squad car. What distinguished this arrest from other Hollywood inebriations was Gibson’s surprising and out-of-place inflammatory remarks. Gibson growled, “Fucking Jews.… Jews are responsible for all the wars in the world.” He then asked the officer, “Are you a Jew?” Mee was indeed Jewish. Gibson refused to get into the squad car and had to be handcuffed.

Less than nineteen hours later, the celebrity website
TMZ.com
obtained a leak of the handwritten arrest report and posted it immediately. On July 29, after a vigorous response from the media, Gibson offered a note of apology: