It looks like Bill Nye, the science guy, is coming out with a new book on evolution, with an excerpt at Popular Science: Is The Human Species Still Evolving? | Popular Science.
We cannot step away from evolution. Our genomes are always collecting mutations, and we are always making mate selections. Are humans preferentially mating with other humans who are tall? Blonde or not blonde?
Are smart people actually producing significantly smarter offspring, who end up making more money and ever so slowly outcompeting other families? Or is intelligence a losing trait, because highly educated couples tend to have smaller families, so when something goes wrong there are fewer siblings left to carry the genes forward? Or since highly educated men and women have babies later in life than those that don’t squander their best childbearing years in universities, do the babies of the highly educated enter the world with more trouble in childbirth, and are they prone to more subtle gene troubles that result from later mother and fatherhood? Cue the spooky music.
When I was younger, I reasoned that evolution had ended for humanity because we lived in organized societies that protected the weak. Without the weak dying in the wilderness, I thought, natural selection couldn’t…select. And without that selection, traits couldn’t disappear nor new ones dominate, and so evolution couldn’t happen. But my understanding of natural selection was simplistic.
First off, just because we now live in societies that, at least sometimes, protect the weak, doesn’t mean that mutations don’t happen. Without the harsh wilderness selection that our ancestors lived in, that probably means that there’s a lot more variation in the human genome than existed, say, 10,000 years ago. Mutations that might have quickly been selected out in hunter gatherer societies have more of a chance in civilization.
But my second misunderstanding was in believing that natural selection is about survival. It is, partly, but it’s more about reproductive success. And animals with certain traits don’t have to be completely unsuccessful reproductively for their traits to disappear. Given enough time and generations, they only have to be slightly less successful than animals with different traits.
And finally, traits that will be successful in a hunter gatherer culture, such as males with athletic ability and aggression, might be less successful in a farming or industrial society. Selection is still happening. It’s just happening at the mate selection and cultural selection level. (Which is actually still natural selection, if you take a long enough view.) Humans have just developed the ability to manipulate our environment, and hence the selection criteria.
Another interesting complication with all this is the development of birth control, which essentially allows us to indulge our reproductive instincts without actually reproducing. That plus the cost of raising additional kids in a modern society means that the most successful people aren’t always going to produce the most offspring. What effect this might have on evolution over the long term is hard to predict.
Of course, as Nye briefly alludes to, this assumes we won’t go through some type of Singularity in the near future, or, perhaps more likely, take control of our evolution with genetic engineering. It might be that the era of unguided evolution on this planet is nearing its end, at least for humans. Possibly.