What I found most surprising was learning that controversy surrounds the assertion that we are still evolving! The alternative hypothesis -- that technological and social innovation have arrested genetic evolution -- seems fantastical to me. The sun does not revolve around the earth; evolution does not bow to mankind.
We're still evolving, but it's far overshadowed by cultural evolution, technology in particular.
Significant evolutionary pressures at present include: rich people having fewer children; increasing infertility and sterility (caused by susceptibility to certain pollutants?); whatever causes SIDS; whatever causes susceptibility to various serious mental illnesses; etc. In short: whatever makes one less likely to reproduce.
But these effects take at least a few generations to be visible. Contrast with our technology a few generations ago - and extrapolate a few generations into the future (we keep searching/inventing, and using the tools we come up with to iterate ever faster).
Think of all the people you know who couldn't function without glasses or medication, and imagine a world where they all died. Evolution does not bow to mankind, but we've thrown sand in the gears for sure.
It's like squeezing a balloon. We haven't alleviated the pressure of evolution, we've only shifted it. While science and medicine have ameliorated many of our biological weaknesses -- genetic or sporadic -- other cues have taken there place. What is (temporally) being selected for is a more interesting question.
Evolution can be increased or decreased easily. Natural selection is a result of death. More death means more natural selection, and less death means less natural selection. We've reduced death tremendously, and hence reduced natural selection.
Sexual selection is quite a different animal, but we can't take as a given that sexual selection increases as natural selection decreases. It might; I just don't know any reason that it would. And there are reasons that even sexual selection would diminish--for various reasons, I don't think anyone today could have nearly as many children as Genghis Khan did.
No, natural selection is a result of differences in reproductive success. We've lowered death, but does that somehow ensue that everyone has exactly the same number of surviving grandchildren? 30% of german women never reproduce. Among female graduates, the figure is 40%. From an evolutionary standpoint, they might as well never have lived.
From an evolutionary standpoint, they might as well never have lived
There is the distinct possibility that they affected the chance for others to reproduce or survive. So you are right about their individual evolution, but they were likely part of group or species evolution.
In bees and other hive insects this effect is most pronounced, as there are only only a few individuals in the hive that can reproduce. But with only them, the hive would die out, so the rest is useful from an evolutionary standpoint.
The point remains that for natural selection to stay the same, decreases in death, sterility, etc. have to be balanced by increases in some other selective force, and you'd have to somehow argue that there was such an increase. Moreover, it has to be something inheritable, not acquired.
My original claim was that it was fantastical to suggest evolution was arrested, not slowed; however, your point is more nuanced and interesting than mine. With this in mind, I'd refine my original statement.
I find the idea of a stable rate of evolution curious. With respect to your argument, we are in agreement: there is reason to suspect that evolution as a reaper has become more tolerant; on the flip side, I'd argue that genetic diversity is increasing, as a consequence of with an unbridled phase of expansion. In this sea of diversity, the genetic victor exists, to be revealed during some future event of punctuated equilibria.
so you're saying that in the far off future, only those who have no self control and takes no responsibilities for their actions will be the survivors.
I don't think "once" is the correct word here. More like "if". Even then it's still a pretty big stretch to think that evolution will not occur with humans, because even if everyone lived forever everyone would likely have children and those children would have children, etc. Evolution continues just at a slower rate probably. And even then people will die from accidents with some greater than 0 frequency. As long as you have reproduction and mutation you will have evolution.
It's a trait particular to humans to announce the end of history every 20 minutes or so. Something in us tends unswervingly towards credulous millennialism, ready for us to all transcend into light or burn to ash.
It would be nice to know what current selection effects actually are; otherwise, it seems like kind of a "well, duh" announcement. After all, everyone knows that some people still have more grandkids than other people do.
I'm surprised this is considered news and that it made the front page. Of course natural selection is still at work. Anyone who finds that surprising doesn't really understand evolution theory.
