Decoding Love - Andrew Trees [78]
Similar MHC genes have also been shown to cause a host of problems for couples. According to one study, partners who have more difficulty conceiving a child share significantly more of their MHC genes than couples who have dissimilar MHCs. Doctors have also found that couples with more similar MHC profiles suffer from higher rates of miscarriage. It even has an effect on sexual fidelity. As MHC profiles become more similar, researchers have found that a woman’s sexual responsiveness to her partner diminishes. She is more attracted to other men, and she is, on average, unfaithful with a greater number of men. With 50 percent of the profile in common, a woman has a 50 percent chance of sleeping with another man. These studies clearly suggest that any woman who is serious about finding a long-term partner should avoid oral contraceptives. By outwitting nature, we may have actually outwitted ourselves and undermined an important element of mate selection—smell.
If a woman does decide to go off the pill, I do have to warn that there will be one unexpected downside if she chooses to use condoms instead—she will no longer have the medicinal benefits of semen. That may sound even more preposterous than the T-shirt study, but it’s the truth. Unlikely as it sounds, semen contains powerful, mood-enhancing chemicals that are absorbed through the vaginal wall (digestion is a different matter, so this doesn’t apply to fellatio). According to a recent study, women who don’t use condoms and have regular sex are less depressed than women who use condoms or women who aren’t having sex.
Of course, women have probably intuitively understood the power of smell all along. A surprising number of women I interviewed said that smell played a crucial role in their dating, and some even claimed that they could immediately “smell” if a man was right for them. One woman even said that she liked to smell her boyfriend’s armpit—and not when he was fresh out of the shower. Not since Walt Whitman have I seen such a ringing endorsement of the sweet smell of armpits. Our hygiene-obsessed society makes it more difficult for women to smell whether a protective partner has the right stuff or not, which might help explain why kissing plays such a large role in most relationships. Our saliva also contains traces of our MHC, so kissing can reveal what our daily showering hides. You do have to exercise some caution when relying on your nose, though. Fragrances can fool even the most astute sniffer, so you need to make sure that you are smelling the unadulterated scent.
FICKLENESS, THY NAME IS FERTILITY CYCLE
It is possible that the chemistry of the body, particularly hormones, also offers an explanation for the fickleness attributed to women. For example, a woman’s ovulation cycle can have a dramatic effect on what sort of man she finds attractive. Studies have shown that during ovulation women find masculine faces more attractive but find feminine faces more attractive the rest of the time (other traits such as voice follow a similar pattern). Women during ovulation also show a greater preference for the smell of symmetrical men. Masculine faces and symmetricality are signs of health, so