Is Sir David Attenborough right? Have humans really stopped evolving?

In a recent interview with the Radio Times, British naturalist Sir David Attenborough said that we are the first species to put a halt to natural selection and as a result, humans have stopped evolving. Is that really true, though? According to other scientists, no.

Natural selection is what drives evolution, and it's usually boiled down to the phrase 'the survival of the fittest'. Members of a species are better adapted to their environment, or they're quicker, or they're stronger, or they have some new body part (like a tail, for example) that gives them an advantage over the other members of their species. Thus they survive longer and produce more offspring, and within several generations the entire species has those better traits.

According to Attenborough, though, humans have pushed beyond all that because, as he puts it in the interview, "we started being able to rear 95–99 per cent of our babies that are born." He doesn't think we're going to go extinct, because we'll find clever and resourceful ways of surviving, but he believes that all of our evolution from here on will be cultural.

Not everyone agrees with Sir David, though. According to an article by Ian Rickard, an anthropologist at Durham University, he and his colleagues were discussing this subject at this past weekend's British Science Festival, and they came up with a completely different answer. Rickard says: "So long as some people are having children and some people are not, natural selection has something else to which it can turn its attention."

The point is that natural selection doesn't necessarily depend on survival. What's really behind natural selection is who is reproducing and how many offspring they have. This doesn't necessarily mean that the strongest, or the fastest, or the smartest will be the ones that drive the evolution of a species.

Also, according to Rickard and his colleagues, natural selection coming to an end would also mean that the environment would have to stay the same. As long as our environment is changing — either by us expanding into places we haven't lived before or the climate changing (by natural and unnatural means) — this will push us to adapt, thus bringing natural selection into play again.

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When it comes to human evolution, we're not undergoing the same level of changes that happened thousands of years ago, but we are still undergoing changes on a more regional scale. For example, studies have recently shown that men in Europe grew 11 centimetres over a century due to improved health. It's quite likely that humanity will continue to evolve with these smaller changes until we're no longer around.

(Photo courtesy: Reuters)

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