(June 8, 2018 at 10:46 am)Clueless Morgan Wrote:(June 8, 2018 at 10:13 am)Whateverist Wrote: If lactose tolerance was developed in the last several hundred years I can see how it could have been selected for. But today I don't see how any advantageous mutation will ever be selected for or, for that matter, how any reappearance of a less favorable form will ever be selected against. Thank you modern medicine.
Evolution doesn't only work by actively selecting for or against mutations though. Evolution also works by genetic drift that can appear to have no current advantage or disadvantage but can develop an advantage or disadvantage in the future.
I'm thinking of an example I read in Dawkins' The Greatest Show on Earth where biologists were doing research on the evolution of bacteria and they discovered that a certain strain of the bacteria developed a mutation in generation M, let's say, that didn't become advantageous to the bacteria until it developed a second mutation in another gene in generation, let's say, X. There was no active selection of genes going on in the bacteria, it all happened by genetic drift in genes that either weren't being expressed or didn't disadvantage the bacteria to the point where it couldn't continue to reproduce and thrive.
Such genetic drift can be occurring right now in humans that we don't know about yet and therefore cannot actively select for or against.
For sure genetic drift or mutations will continue to occur, but I just don't see it resulting in more or less babies produced any longer. There are so many other reasons people do or don't have kids that I doubt if any mutation is going to make a measurable difference. It isn't as though as a species we are disposed to produce as many young ones as possible unless something stops us .. well except for Khem maybe.
