Gene frequencies for the ABO alleles vary geographically. For example the I^A al
ID: 24860 • Letter: G
Question
Gene frequencies for the ABO alleles vary geographically. For example the I^A allele makes up nearly 50% of the genes for blood type among Australian Aborigines, about 25% in Central Asian populations, and 0% in peoples native to South America. No blood type has sufficient selective advantage over another to explain these regional differences. From these facts, what can you infer about the history of our species? Did humanity develop as a large and continuos population spreading out across the planet, or did we disperse while still living in small scattered groups?Explanation / Answer
* Humanity develped, while they dispersed living in small scattered groups. Ancestral human population remained as small, isolated groups. When population of a group increased, some of them would leave their isolated pockets and mixed with other groups. The population migration to several places around the world occurred in a number of waves, not at a time, from Africa.
This waves of migration gave rise to different humaities. Geographical isolation created enough differences in theri genotypes, subject to environemtnal pressure and natural selection. We have different blood groups that were inherited from different Homo cousins. Neanderthals and erectus population interbred, giving rise to new bloodlines.
The migration of population created different races, and environmental pressure offered advantage with certain genotypes. For example, O blood group individuals are less susceptible to syphilis (native Americans belong to blood group O, and syphilis is endemic among them). Group A and B are more resistant to choleral, while AB offers most resistance. O group individuals are more susceptible to cholera. B group offers less resistance to plaque than do A type blood.
European races typically have very low frequency of B allele and high frequency of A allele. Asiatic populations have high frequency of AB alleles.
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