By Nick Hainsworth
In Part I of this blog series, we learned that the physical geography and climate of earth affected the migration of people out of Africa and to the rest of the world. Part II and III focus on two ways that migration affected humanity, and how these things can help teach us even more about humanity’s origins and migrations. These things are genetic and linguistic diversity.
Genetic diversity is the “range of different inherited traits within a species.”[1] For example, dogs have a plethora of different genetic traits, and breeders will specifically breed dogs with traits that we want, giving us the cutest, cuddliest, friendliest dogs possible! There is also genetic diversity among humans. This diversity is the reason we have different facial features, body types, and skin tones. Compared to other species, however, humans are remarkably similar genetically. If you took two random humans, they would only differ on average about 0.1% genetically.
One of the reasons we know as much as we do about the origin of humans and their journey out of Africa is because of our genetic makeup. Two important facts help us understand our history. First, the genetic makeup of people outside of Africa can also be found in Africa. Because humans outside of Africa don’t have any genetic traits that aren’t also found in Africa, we can assume they all came from Africa, rather than evolving somewhere else in the world around the same time. Second, the genetic diversity of humans within Africa is much greater than the genetic diversity of humans outside of Africa. This is why we assume that a small group of 150-1,000 people leaving Africa is responsible for populating the rest of the world. That isn’t a lot of genetic diversity to go around, which means the rest of the world has only this small group to thank for their limited gene pool.[2]
What would have happened if there had been more than one group that left Africa? What would our genetic makeup look like? If the climate had been more conducive to migrating outside of Africa, we may have had several migration movements that survived, leading to greater genetic diversity in humans outside of Africa. Remember, though, that even within Africa, the genetic diversity in humans is still very limited. Despite our apparent differences, at a fundamental genetic level, we are all very much the same.
[1] https://imet.usmd.edu/activities/what-genetic-diversity
[2] https://www.ashg.org/wp-content/uploads/2019/09/genetic-variation-essay.pdf
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