Sunday, February 15, 2009

Birth Control Side Effects

One of the bits of scientific research that I have come across relates to the role of scent in human sexual attraction.  To simplify, people are attracted to the scent of a different immune system.  This makes sense, because a kid who inherits a wider range of immune markers will have a stronger immune system and be more resistant to disease.  More generally, this scent effect makes people less likely to inbreed and more likely to find mates with different genes, generating hybrid vigor.

However, women who are pregnant prefer the scent of family members, because the family is more likely to support them and there is no need to seek a mate.  And because birth control pills fool the body into believing that the woman is pregnant, women who are using these contraceptives will be attracted to men who smell like family, men who have similar immune systems.  This means that a woman who chooses a husband while taking birth control pills will choose someone that she will not be attracted to when she stops taking contraceptives.

I have seen people comment on everything I have related above, but they always fail to think about the logical implications of this effect.  This difference in attraction could be related to problems with dating.  Presumably, men are also attracted to women with different immune systems.  Their bodies are not being affected, so they will make an 'accurate' assessment.  If the women they are attracted to is taking birth control, then the man will feel a strong attraction but then be rejected.  Similarly, the men who women are attracted to will not share the attraction.

More important, and more disturbing, is the implications for the genetic fitness of the resulting offspring.  Some women may get a divorce when they stop being attracted to their husband.  But most will not.  Almost everyone says that it is common and natural for sexual attraction to fade over the course of a marriage.  And if the couple waits a few years to have kids, then they will be connected by bonds of affection and be committed to each other.  So they have children, and their children will have a weaker immune system than children who come from parents with different immune systems.

This is just speculation, but I believe this effect is responsible for a lot of things that currently have no good explanation.  The use of oral contraceptives before marriage has been widespread for over 40 years now, which means that a significant fraction of an entire generation has been born to parents who, in the natural course of events, would never have been attracted to each other.

First, there has been a massive and mostly unexplained increase in the number of cases of asthma in the last few decades.  Asthma is directly related to a problems with the immune system.  And it isn't just asthma.  The prevalence of a lot of random immune-related diseases seems to be increasing.

Second, there has been a large increase in the demand for reproductive medicine.  Many couples are finding that they have difficulty having children.  It is known that a fetus who inherits similar immune system genes from both parents is less likely to come to term. 

This could explain the debate about the long-term effects of birth control.  There is no evidence that the pills themselves cause any damage to the body.  But it is likely that couples who got engaged under the influence of birth control will have problems having children, so there will be a statistical relationship between birth control use and later fertility problems.

These kinds of problems will only get worse.  The generation of children born to parents who met under the influence of oral contraceptives is now choosing spouses and having its own children in the same manner.  This second generation will likely have even weaker immune systems, and I would not be surprised if a large number of random genetic problems start to appear as well.

People need to know about this.  Women need to know that choosing a husband while on birth control could lead to an unhappy marriage and sick children.  But nobody is talking about this effect.

I'm not really surprised.  This research does not fit with anybody's ideological agenda.  Conservatives don't like to admit that people's choices are so strongly affected by biology.  Liberals don't like to admit that there could be something wrong with birth control.  But they are both wrong, and people will continue to suffer as a result.

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