It's not anemia that gives you advantage, but the gene that gives you anemia. People who carry one copy of the gene (who are heterozygous), don't have anemia but have the advantage, while people who carry two copies (are homozygous) are at a huge disadvantage due to anemia. This is a classic example of heterozygosity advantage.

Sickle cell anemia is Mendelian and recessive. So if 2 carriers (Rr and Rr) have kids, 50% of the children will be strictly superior (carriers), 25% will be normal, and 25% will die young. Not a bad outcome, especially if you have a lot of kids to reduce the variance.

> 50% of the children will be strictly superior (carriers)

Is that domain nomenclature? Because I wouldn't call having to be careful who procreate with otherwise risk losing 25% of my children from that relationship as "strictly superior"...

2/4 resistant to malaria with no side effects and 1/4 dying is much much better than 4/4 dying from malaria

pretty good considering something like half of all human beings who ever lived died of Malaria!

I am mildly disappointed to learn that this is probably an overestimate, although it is pretty significant http://factmyth.com/factoids/malaria-killed-half-the-people-...

Thanks for calling it out! I think I first heard this from Plasmodium researchers, and in my mind the claim has strengthen over time. A better statement would be: "“Malaria could have potentially killed nearly to half the people who ever lived, predominantly children”."

And this is based off the idea that for most of human history people have lived in Sub-Saharan Africa, where the majority of people who lived died as children, and the predominate cause of death was Malaria.