FOX: "We keep marrying other species..."

[rpggal 332]

7 hours ago, ezrajones said:

No, sickle cell is endemic to Africans. Malaria is not a thing in America but sickle cell is still a highly prevalent disease in black families. And no, Africans are the least diverse because they've stayed in the same space for much of their existence. The other races have left (Druze, Bedouin, Caucasus, European, Asiatic, Maya etc.) and become much more diverse breeding-wise than sub-saharan Africans. Even Nordic whites are more diverse genetically than sub-saharan Africans (where sickle cell is most prevalent). 

Blacks have a higher rate of the disease because they descend from people that originated geographically from areas that do have malaria and the sickle hemoglobin allele. I will correct what I said though in saying it is endemic *wherever* malaria is endemic, what I  meant is that the correlation been malaria prevalence and sickle cell prevalence along populations that have sickle hemoglobin in their gene pool is profound and at this point it is undeniable that sickle hemoglobin *in the populations it exists in* is under positive selective pressure because of malaria resistance and not a result of inbreeding aka low population genetic diversity. Here's the evidence on that.  http://www.nature.com/articles/ncomms1104

Africans are the most genetically diverse of any race, that has been confirmed by many studies, but here's one citation for you. http://www.nature.com/ng/journal/v36/n11s/full/ng1435.html

Your evolutionary theory is wrong. Migration causes evolutionary bottlenecking and *decreases* genetic diversity within a population. It is always a subset of the population that migrates, not the whole thing, so that subset starts a new population all on its own from a much less diverse gene pool than the original population had. It's called the founder effect. When the first humans left Africa, they were only a small sampling of the total genetic diversity already in Africa all those tens of thousands of years ago (which has only grown since then because new mutations arise in every generation), and consequently every other race of humans on the planet is less diverse because they originated from this smaller genetic sampling, whether interracial breeding was common in those areas or not. If you read the article I linked, it states that the genetic diversity between races/continents is 9x less than the genetic diversity within a race/continent, meaning interracial breeding would do very little to increase population diversity, the majority of which comes simply through random mutation and time, minus any bottlenecks.