Human gene frequencies for the ABO blood group vary by geographiclocation. Type A is found in 50% of the genes in Australianaborigines, 30% in Blackfoot Indians, and absent among the nativesof South America. Type B is the rarest form throughout the worldwith the highest occurrence in Central Asia, being 30%. No bloodtype has a selective advantage over another.

What can you propose about the evolution of the humanspecies?