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Old 02-27-2017, 02:48 PM
Hari Seldon Hari Seldon is offline
Join Date: Mar 2002
Location: Trantor
Posts: 11,401
I read somewhere that eyes appeared to have evolved independently up to 40 times.

One place that evolution might take place and even quickly would happen if we somehow succeeded in wiping out malaria, whether by a gene drive mechanism or otherwise. You would see the sickle cell trait disappear rather quickly in evolutionary terms. Maybe with a few dozen generations or certainly a few hundred.

On the other hand, we are unlikely to evolve a lack of appendix. I am very sensitive to this because I am one of three none of whom would have survived to reproductive age without the availability of appendectomies, which is the sort of thing that ought to generate strong evolutionary pressure. But the other side of this coin is something I read somewhere that smaller appendices are more likely to get infected than larger ones. So the appendix is unlikely to wither away, although I suppose it could just disappear somehow.

This illustrates the fact that evolution can work only with the material it has at hand. It can happen quickly or slowly, but every step has to give a selective advantage.