Question: How likely is it that humans will evolve any further and to what extent will this evolution be?

David Freeborn answered on 27 Jun 2013:

Yes, humans are still evolving. There is great genetic diversity between humans, and not every human survives to reproduce future offspring, so it’s inevitable natural selection is still going on.

In the past few thousand years, humans in pastoral communities evolved lactose tolerance, so that they could easily eat milk and cheese. In China, where early civilisations did not make use of milk, only 1% have the gene for lactose tolerance.

Today, the rate of natural selection is very low. Human beings with genetic disorders that would cause them to die in the wild, or even a century ago, now frequently go on to live fulfilling and rewarding lives, and may often reproduce. More generally, people who are e.g. short-sighted no longer have any evolutionary pressure against them: they can just wear glasses or contact lenses.

A few scientists are worried this means that the human species will be gradually evolving to become weaker or less intelligent: because harmful mutations are much more common than beneficial ones.

Realistically though, this isn’t going to be a problem. By the end of the next century, I would be very, very surprised if some degree of genetic modification or selection of humans isn’t the norm. People will want to start selecting what characteristics their future children will have. The technology is now there: I think it’s only a matter of time before it becomes affordable and culturally acceptable.

That’s a really exciting possibility: we can start selecting for genes that lead to humans becoming smarter, more compassionate, fitter, stronger, more disease-resistant more long-living or more talented as a species.

We also need to be very careful though. We don’t want to reduce the genetic diversity of our species, and we also need to make sure we don’t cause any unexpected side effects by changing particular genes, so we need to be very careful about how we select which genes to choose. We also need to make sure such a service is free and available for all: otherwise rich people will be able to make themselves more intelligent or stronger than others: that could be very dangerous. A big worry is companies copyrighting or patenting certain parts of the genetic code, so people would have to pay them for access to this. This is already happening with genetically modified crops.