RE: Is evolution still possible on a large scale?
October 1, 2010 at 4:55 am
(This post was last modified: October 1, 2010 at 5:13 am by Anomalocaris.)
Evolution is not just mutation, selection, and speciation. A single species' genetic makeup can gradually change without there ever arising a new species, this is also evolution. A species' genetic makeup can change without mutation because sexual reproduction creates new genetic combinations all the time. Probability Mathematics of sexual genetic combination is such certain genes will graduall disappear even if they impose absolutely no disadvantages to its owner, while others will grown to become present in the entire population even if they offer absolutely no survival advantages. This is random genetic drift. In fact there is good evidence to suggest the many differences between races arose from genetic drift, not selection pressure. So our species is evolving even if our social system and medical technology cancels out all overt survival and reproductive advantage of good genes, and compensates for all overt survival and reproductive handicaps of bad genes, and we all travel a lot and mate all over to ensure no population gradually speciate by genetic isolation.
To add on top of this spontaneous genetic drift, there is also the fact that genes can change our response to selection preesures so subtlely that medical technology would not be sensitive to it and social convention would not be attuned to it. But even subtle advantages and disadvantages, when compounded over many generation, can totally alter the genetic make up of our species. An example would be a mutation that alters a woman's chances of suffering an spontaneous natural abortion during early pregnancy. Natural termination during very early pregancies almost always go unnoticed. But it's occurrence has a significant effect on a woman's real fertility,especially if she attempts to get pregnant at a later age. A gene that makes a woman less likely to suffer early natural abortion thus materially increases her chances of passing on her genes as surely as if it could make her run faster before a hungry lion. But because the thing this gene acts on, early stage natural termination, is not easily observed, this selection advantage, or the lack of it, will not pomp any medical or social response. So over many generation, a version of this gene that reduces early termination will gradually dominate, and the alternative gradually disappear. Natural selection would haves acted on us and forced us to evolve without our knowledge, much less consent.
So humans are still evolving, and it's not even within our power to stop it if we consciously set out to do so.
To add on top of this spontaneous genetic drift, there is also the fact that genes can change our response to selection preesures so subtlely that medical technology would not be sensitive to it and social convention would not be attuned to it. But even subtle advantages and disadvantages, when compounded over many generation, can totally alter the genetic make up of our species. An example would be a mutation that alters a woman's chances of suffering an spontaneous natural abortion during early pregnancy. Natural termination during very early pregancies almost always go unnoticed. But it's occurrence has a significant effect on a woman's real fertility,especially if she attempts to get pregnant at a later age. A gene that makes a woman less likely to suffer early natural abortion thus materially increases her chances of passing on her genes as surely as if it could make her run faster before a hungry lion. But because the thing this gene acts on, early stage natural termination, is not easily observed, this selection advantage, or the lack of it, will not pomp any medical or social response. So over many generation, a version of this gene that reduces early termination will gradually dominate, and the alternative gradually disappear. Natural selection would haves acted on us and forced us to evolve without our knowledge, much less consent.
So humans are still evolving, and it's not even within our power to stop it if we consciously set out to do so.
