- Early humans evolved to have dark skin color around 1.2 million years ago, as an adaptation to loss of body hair that increased the effects of UV Radiation. Before the development of hairlessness, early humans had reasonably light skin underneath their fur, similar to that found in other primates. The most recent scientific evidence indicates that anatomically modern humans evolved in Africa between 200,000 and 100,000 years ago, and then populated the rest of the world through one migration between 80,000-50,000 years ago, in some areas interbreeding with certain archaic human species (Neanderthals, Denisovans, and possibly others). It seems likely that the first modern humans had relatively large numbers of eumelanin producing melanocytes, producing darker skin similar to the indigenous people of Africa today. As some of these original people migrated and settled in Asia and Europe, the selective pressure for eumelanin production decreased in climates where radiation from the sun was less intense. This eventually produced the current range of human skin color. Of the two common gene variants know to be associated with pale human skin, #1 (Me1r) does not appear to have undergone positive selection, while #2 (5LC24AS) has undergone positive selection.
- Positive selection is the process by which new advantageous genetic variants sweep a population. Positive selection, also known as Darwinian selection, is the main mechanism that Darwin envisioned as giving rise to evolution.
- Positive selection is the process by which new advantageous genetic variants sweep a population. Positive selection, also known as Darwinian selection, is the main mechanism that Darwin envisioned as giving rise to evolution.