Migration and Genetic Mutations from Africa to the rest of the world
Human skin color is a result of evolutionary processes that have unfolded over tens of thousands of years. Early humans in Africa had dark skin, which provided them with protection against harmful UV radiation in sunny savannah grasslands. However, as human migration out of Africa began around 60–70,000 years ago, diverse skin colors emerged due to genetic mutations and natural selection.
The migration of humans out of Africa was not a simple one-way flow; rather, it involved multiple migration events and movements back and forth between different regions. Notably, significant migrations started around 60–70,000 years ago, leading to the spread of humans across the Eurasian landmass. Evidence suggests that humans began leaving Africa as early as 120,000 years ago, but the most significant migrations related to skin color diversity occurred around 60–70,000 years ago.
Around 70,000 years ago, humans underwent a stable expansion into the Northwest Arabian Peninsula and the Middle East. It was during this period that a mutation occurred in the kit ligand gene, impacting melanocyte production and the skin pigment molecule melanin. As different populations migrated from the Northwest Arabian Peninsula, they carried this mutation with them.
The genetic mutation affecting human skin color is present in modern humans of Middle Eastern, Asian, North Central, South American, or European ancestry. Conversely, this mutation is absent in people with sub-Saharan African ancestry. Additionally, genetic mutations in European populations led to selective advantages for lighter skin in regions with long, dark winters.
Several key genetic mutations have been identified as crucial factors in the development of diverse skin colors. These include mutations in the slc24a5 and slc45a2 transporter proteins, which played significant roles in melanin production in European populations. Similarly, the population migrating out of the Arabian Peninsula experienced a genetic change in the mfsd12 gene, leading to a shift in skin pigment production towards feo-melanin.
As these mutations continued to unfold, genetic changes occurred independently in both European and Asian ancestral human populations, such as mutations to the Oca2 and mc1r genes. These genetic mutations and natural selection eventually led to a linear pattern between human skin color and latitude. Lighter skin became beneficial in northern latitudes with less sun exposure, while modern humans at low latitudes tended to have darker skin to protect against intense sunlight.
The evolution of human skin color is deeply meaningful and serves as a basic biological trait for the human species. It is intricately tied to cultural richness and the weight of historical atrocities, yet it remains a fundamental biological trait that has been constant throughout the existence of humans. These evolutionary processes in response to environmental factors have given rise to the diverse array of skin colors that we see in the world today, underscoring the dynamic relationship between genetics, environment, and human adaptation.
