Exactly what I was about to say. The ill effect of the sickle-cell anemia is far [i]far/i] outway by the positive effect of HIV resistance.
Also, mutations are what causes evolution, not all mutations are beneficial but some are. A competitive eviroment is required for evolution to take place, so any advantage that an evolution can give is extremely valuble and that desirable characteristic can be can be passed on to the next generation.
And by the bay, I study evolution at GCSE level and I got 100% in the mock exam for it, so don't say I don't know enough about it.
|