Is evolution over? Answered
Geneticist Professor Steve Jones has said that human evolution may be over, and that we may now, as a species, be on the slippery slope to extinction.
He's not saying evolution in general has stopped, just ours.
His theory is that our development and exploitation of technology has de-coupled human development from natural selection. Conditions which would have meant an early grave for our ancestors, through starvation or other side-effects, are now barely considered as inconvenient, let alone life-threatening.
Personally, suffering asthma and 8 dioptres of short-sight, I would have quickly starved to death in our hunter-gatherer days, unable to keep up with prey animals or to see well enough to tell "nutritious" from "poisonous".
What this means is that we have a rate of survival to age 21 that is almost 100%, double what it was in ancient times.
At the same time, our supporting technologies, particularly in medicine, mean that there is a growing accumulation of deleterious genetic conditions in the general gene pool.
Increases in world travel have also meant that the differences between different human populations, already low, are getting smaller, as openness and acceptance of other cultures has started to homogenise our phenotype.
The result - we are isolated from natural evolutionary pressures, so there is nothing to stimulate natural selection, nothing to weed out potentially-dangerous mutations. We are stagnating.
So, what next?
On the one hand, the pessimistic view is that, at some point, our genome will become so laden with hazardous mutations that we will cease to be viable as a species. We will be unable to reproduce successfully.
On the other hand, maybe other species, still closely linked with natural selection, will continue to evolve until they supplant us. The obvious choices are chimps and gorillas - if we don't drive them to extinction.
Or maybe our heirs are currently underwater - dolphins, maybe? Or maybe they won't be mammals - octopus and squid are highly intelligent. Heck, even slime moulds have been shown to be capable of solving mazes!
On the gripping hand, maybe we've out-evolved evolution? The optimist in me hopes that technology will out-pace the fuse on the genetic timebombs we have become. Maybe medicine will be able to edit our DNA, or write it afresh, truly triumphing over nature?
Article stimulated by this BBC blog entry.
Other linked news items.