Quote:
Originally posted by Brinny Baby
A mother with 3 arms would survive/take care of her youth better than a mother with 2 arms. They'll get work/jobs done quicker.
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To indulge you, a woman being born with three arms is not a common enough mutation to have any influence on the gene pool. Also, in this day and age, having three arms would probably do more harm than good given that all of our technology and infrastructure is designed for people with two arms.
A common theory for why the incidence rate of sickle cell anemia is so high in regions of Africa is that the same genetic mutation for sickle cell anemia confers a partial tolerance to Malaria. And that being heterozygous (having one dominant and one recessive allele) for sickle cell anemia confers no phenotype of the disease while still offering the resistance to Malaria.
