[maxerbubba]

That's not how evolution works... random variation, sometimes detrimental, will sometimes lead to advantage

[monocasa]

Sometimes both. Sickle cell anemia gives you slightly better odds of surviving malaria for instance.

[xyzzyz]

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.

[mruts]

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.

[kbenson]

> 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"...

[rangibaby]

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

[wespiser_2018]

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

[lazyasciiart]

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-...