why is it that dominant alleles are often the “better” ones? Heterosis (matings from different genetic pools) is often considered to be an advantage to the child since it emphasizes the stronger dominant alleles. Whereas inbreeding is dangerous because it increases the risk of two recessive alleles brunching together. The question is - why is it that certain phenotypic characteristics have been assigned to dominant alleles? Why was it that darker skin/eyes belong to dominant alleles in the first place? What exactly are the origins of such alleles in humans? Of course, recessive alleles are often rare because individuals with both copies of a recessive allele often die before being able to propagate (whereas there may have been many different types of dominant alleles - and the ones that were dominant + beneficial beat out the ones that were beneficial + non-dominant). But this does not explain the origins of the connections between such alleles and phenotypic characteristics. Can someone help me out? And what of recessive non-dominant traits that are beneficial? I'm talking about traits that are beneficial even when homozygous - so sickle-cell anemia and malaria resistance is not one of them Thanks!