Is the Pill Affecting Human Evolution?
The development of the birth control pill in the early 1960s revolutionized human sexuality. More than 40 years later, scientists are beginning to wonder if the pill is having an impact on more than just menstrual cycles and sexual activity. Some recent studies have suggested that contraception using hormones may affect such hard-wired instincts as mate choice and partner preferences, which may lead to a weakening of human beings as a species.
From an evolutionary standpoint, heterosexual women who are ovulating usually prefer dominant men with masculine facial characteristics like a prominent, square jaw. They also prefer men who appear genetically different. Furthermore, heterosexual men tend to be more attracted to women who are ovulating than those who are not. However, since the pill mimicks pregnancy, researchers believe that women on the pill may ignore or not even experience some of these instinctual attractions. "The use of the pill by women, by changing her mate preferences, might induce women to mate with otherwise less-preferred partners, which might have important consequences for mate choice and reproductive outcomes," said Dr. Alexandra Alvergne of the University of Sheffield and the author of a new study on the impact of the birth control pill on human evolution.
What do these pill-induced changes to partner preferences really mean? "One prediction is that offspring of pill users are more homozygous than expected, possibly related to impaired immune function and decreased perceived health and attractiveness," wrote Alvergne and her co-author Dr. Virpi Lummaa. Although more studies need to be performed, these researchers contend that the pill, for all the sexual freedom it granted, may actually be inhibiting sexual viability. Alvergne believes that future research should focus on two specific areas of study: the effect of the pill on marriage and its effect on the ability of couples to reproduce.
Despite these findings, there are, of course, skeptics. Dr. William Hurd, a reproductive endocrinologist at University Hospitals Case Medical Center in Cleveland, said, "If you don't take into account society maybe we're all animals, but in social situations I don't think there are many women who change who they would mate with at different times of the month. It might change desires or perceptions but, gee whiz, that's a long stretch to changing who you would date, or even who you would go to dinner with." He believes there are other, more significant influences on contemporary human mating rituals, namely the Internet. "Probably the biggest change in my lifetime is how people meet each other: online and using programs that match them for compatibility," he said. "That's probably going to have a massive effect on how people end up dating and ultimately reproducing. Just because you like someone with a square jaw in the middle of your cycle probably doesn't affect who you end up with."
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The theory around some of
The theory around some of this is significant, but needs to be considered as a whole. It is true that women prefer higher testosterone men when they are ovulating, i.e., right around the time they are most likely to conceive. However, that's just when they're ovulating. Do they not show a preference otherwise? Do they prefer other types of men? The key there is that there's some evidence that that's the case, but why?
It begins to make sense when you add two more elements in. First is that there's another, unmentioned aspect of hormones, this time from the male side. Statistically speaking, those manly, high testosterone males you find so hot are also less likely to like kids, and less likely to not sleep around. Either way, that guy isn't likely to give you his full resources, either because his resources are divided or because he just didn't care about your kids. You're on your own.
But you, as a woman, want his genes, because they're "healthy," right? Well, maybe, but more importantly you want his genes because you want a son WHO WILL ACT LIKE HIS FATHER. You can only have so many kids, but a man who spreads his seed widely will give you the best shot at having a bunch of descendants. So, the women who (likely unconsciously) had children by "manly bad boys" might have had a slight evolutionary advantage.
But, wait...what about keeping the kids alive? Don't you need that guy's support? Well, yes, you do, but you can't count on it. So, that's where the other guys come in. You don't want their kids as much, because, well, they won't be as ambitious, but you do know you can keep them around. So, you do keep them around, even genuinely like them. Just not when you're likely to make a baby. Then, you like those other guys. And, if you can pull it off, you win the perfect situation for a woman; a dedicated guy who helps with your a male son THAT HE ONLY THINKS IS HIS. Who will carry your genes unto the world.
Does birth control mess this up? Absolutely. But is that bad? Are secondary sex characteristics, old notions of masculinity the things that define the fitness of our species? Hardly. We're creating a scenario where women have kids with the person they choose to, not who their variable desires choose to, and that's a good thing. Because they'll have more of a chance of choosing the right guy.
Now, the secong problem, related to the immune system, IS an issue. Apparently women and men like the smell of men who have immune profiles most different from their own (which makes for kids with stronger immune systems), but that gets reversed in women who are on birth control--they like the guy with a profile like their own. So that component would make for less healthy children. But it's a different issue than the masculinity one, and if we're breeding fewer assholes at the expense of a somewhat diminished immune system, it's one I might not balk at.
Natural selection does not
Natural selection does not always favor the best individuals, just the ones that reproduce the most. It seems that the pill does subvert our genetic desires at least with regard to sexual selection, but I would hardly condemn it as weakening the species. Evolution is always a step behind environment conditions, so changing desired traits could be good. Up until recently, strength was a preferable trait to intelligence- and natural selection confirmed it. Now, since our culture has radically changed, evolution can't keep up. When a women is pregnant, she will seek a stable relationship over a wild one. If this subverts sexually selection to encourage intelligence, this could be benevolent to the species.
Also, if this should turn out for the worse, we could simply give hormones that emulate the ones that occur during ovulation.