Featured Topic 4/09: Natural Selection Today

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Humans today aren't subjected to natural selection the same way we used to be.  In the early days of humanity, people with poorer vision or slower reflexes were more likely to end up being unable to find enough food to survive, or possibly becoming food for a saber-toothed tiger.  Today, though, the only things which frequently cause people to die before they can reproduce are disease and accidents, to which just about everyone is equally susceptible.  So it isn't initially obvious what, if any, selective pressures there are that still affect humans in the present.

Daniel Seligman, in his book A Question of Intelligence, points out a rather worrisome trend in this area.  According to several studies conducted over the past 30 years, fertility rates are negatively correlated with intelligence—meaning that people with low IQs tend to have more children, and have them sooner, than people with high IQs.  When you think about this, isn't entirely surprising that it's the case.  It's easy to imagine that people who have children as teenagers are less intelligent, on average, than people who wait until their 20s or 30s for it.  And because of the inevitable effects of natural selection, if people with low intelligence have a higher rate of reproduction than people with high intelligence, over multiple generations this will cause humans in general to become dumber.

With this in mind, here is this month's topic:  Should it be considered a problem that natural selection is favoring humans becoming less intelligent?  And if so, what should be done about it?

My opinion about the answer to this question is something that's changed over time.  Until around five years ago I was a Social Darwinist, meaning that I thought it was important for society to be structured in a way that encouraged natural selection.  As is pointed out by Mainstream Science on Intelligence, an article published in the Wall Street Journal and the psychology journal Intelligence with the signatures of 52 specialists in this area, intelligence is very strongly correlated with economic success—regardless of race or family background, more intelligent people earn more money on average than less intelligent people do.  As a Social Darwinist, I thought that if there weren't any government handouts for low-income people, perhaps they wouldn't have enough money to raise families, and natural selection could be made to favor people with high intelligence rather than the opposite.  While this system seems unkind to the people who would end up losing out under it, the idea is that this cost would be outweighed by the overall benefit of humanity becoming smarter.

I still think that something like this would be worthwhile if it were possible, but what I've realized over the past five years is that it isn't.  The problem is that there simply is no such thing as "not enough money to raise a family".  When one looks at people in third-world countries who earn less than five dollars a day, this doesn't prevent them from having kids—if anything, they end up having more children because their children can help them to try to earn money.  So if anyone is hoping to create a society where intelligence correlates with reproductive success, getting rid of handouts to poor people is not the way to do it.

A second way to try and accomplish this is using eugenics, where the government gets directly involved preventing certain people from reproducing, but that has its own set of problems.  The simplest of them is just that historically, no government has ever been able to exert this kind of power without eventually starting to abuse it.  The most obvious example of a failed attempt at eugenics is Nazi Germany, in which an attempt to make sure only "genetically superior" people could reproduce gradually morphed into a system of persecution based on race, religion, political preference, and other traits which had nothing to do with what eugenicists normally care about.  Eugenics policies of the United States in the early 20th century didn't stray quite this far from their original purpose, but even in the U.S. people were occasionally sterilized against their will for no reason other than their race—as though the people running this system had completely forgotten the distinction between a difference in average intelligence between races, and the idea that every member of a certain race has lower intelligence.

However, even if it were possible to implement a eugenics policy while avoiding this kind of corruption, there's also a much more fundamental problem with the idea.  In the early 20th century, it was widely assumed that it would be easy to identify which genetic traits we should want natural selection to favor in humans:  intelligence, physical endurance, good eyesight, and so on.  But the reality is far more complex than this, because what genes make one individual more "fit" than another is almost always subjective, even when it comes to traits such as intelligence that are seemingly without a downside.  As Gregory Cochran and Henry Harpending point out in this paper, the same genes which code for higher IQ also place people at greater risk for a number of hereditary diseases.  And as a result, in at least one population of humans where natural selection has favored intelligence especially strongly, these diseases have also become much more prevalent than they are among the rest of humanity.  Even if a government were able to successfully implement a eugenics policy that favors intelligence, it would inevitably lead to a higher rate of these diseases also.

So if eugenics is a bad idea and Social Darwinism isn't possible, then what can be done about the current selective trend towards lower intelligence?  Fortunately, there's a third possibility which might become a reality soon.  As scientists identify the functions of more and more genes in the human genome, it's becoming possible for parents who use in vitro fertilization to specify which genetic traits they want their offspring to have.  As stated in this article, it's already possible for prospective parents to make sure the embryo they implant doesn't have certain genes which would result in an elevated risk for cancer, so it soon might also be possible for them to make sure it has genes for above-average intelligence.  And since these decisions would be made on an individual embryo-by-embryo basis, parents would be able to avoid the specific combinations of genes which result in hereditary diseases.

This solution isn't without its own set of pitfalls.  At the moment, parents are only able to choose from a selection of embryos produced by their own eggs and sperm, but it's easy to imagine how far this field of "designer babies" could go.  Will parents one day inject non-human genes into their embryos, based on ridiculous fashions for kids with traits like bioluminescent hair?  Still, virtually every scientific advancement has its downside—such is the price of progress.

—Agahnim