Even though it’s very hot to have a large mane the benefit of attracting mates and successfully producing & rearing young since you have that large mane outweighs the costs. Females who chose these males were more “successful” (more, healthier young) and therefore had a greater opportunity to pass on the trait of being attracted to longer darker manes to their daughters and the trait of having longer, darker manes to their sons.
Small founder group, less genetic diversity than Africans All white people around the world are descended from a small group of ancestors 100,000 years ago (Chinese are white people!)
South & Central American Indians were nearly 100% type O for the ABO blood system. Since nothing in nature seems to strongly select for or against this trait, it is likely that most of these people are descendants of a small band of closely related "founders" who also shared this blood type
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