Homo sapiens (modern humans) appeared approximately 180,000 years ago, but stayed in one location around bodies of water in central Africa for almost 100,000 years, before they dispersed throughout the rest of the world. This is why African DNA is more diverse than that of people anywhere else in the world (and black DNA continued to change during slavery, as well).
A genetic mutation that occurred thousands of years ago might be the answer to how early humans were able to move from central Africa and across the continent in what has been called "the great expansion."
By analyzing genetic sequence variation patterns in different populations around the world, three teams of scientists demonstrated that a critical genetic variant arose in a key gene cluster on chromosome 11, known as the fatty acid desaturase cluster or FADS, more than 85,000 years ago. This variation would have allowed early humans to convert plant-based polyunsaturated fatty acids that are necessary for increased brain size, complexity and function, into nutrients. This meant that early humans didn’t have to rely on just one food source, fish, for brain growth and development.
Researcher Floyd H. Chilton says, "This may have kept early humans tethered to the water in central Africa where there was a constant food source of DHA. There has been considerable debate on how early humans were able to obtain sufficient DHA necessary to maintain brain size and complexity. It’s amazing to think we may have uncovered the region of genetic variation that arose about the time that early humans moved out of (Africa)."
Once this trait arose, it rapidly spread throughout the population of the entire African continent. Researcher Joshua M. Akey says, "I find it remarkable that we can make inferences about things that happened tens of thousands of years ago by studying patterns of genetic variation that exist in contemporary populations" (NOTE: Subscribers can still listen to this show).
Our immune systems are still racial, even here in the multicultural US. Genetics show that people of African descent have a much higher rates of hypertension, type 2 diabetes, stroke, coronary heart disease and certain types of cancer.
Chilton says, "The current observation provides another important clue as to why diverse racial and ethnic populations likely respond differently to the modern western diet."
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