I came across an interesting article called “Odd Cause of Humans’ Dark Skin Proposed”, which states that skin cancer could have directly driven evolution of dark skin in humans. According to the study, people who have albinism, which is an inherited disorder that prevents human from making black or brown pigments, almost die of skin cancer at young ages. The study suggests that the early death of albino people might be the reason why early humans evolved dark skin.

Individuals with white skin are more vulnerable to skin cancer than people with dark skin. For instance, the Skin Cancer Foundation reported that black or brown pigmented skin has a sun protection factor of 13.4, which is relatively higher than that of the white skin (3.4). When hunter-gatherers began to lose their body hair to keep their body temperature cool during their excessive movement for hunting and gathering, they probably had light skin similar to the chimpanzees that has white skin under their fur. However, the article stated that humans evolved to have dark skin about 1.8 million years ago, then evolved light skin again after they migrated to higher latitudes from Africa.

The paper mentioned that skin cancer itself could have driven humans to have dark skin. In addition to the fact that the probability of developing skin cancer is significantly higher for albino people than for people with darker skin, almost all albino people in Africa developed skin cancer at early ages due to high prevalence of outdoor labor. These early cancers in lighter skinned humans lead them to die before reproduction, thus leaving mostly darker skinned individuals to pass on their genes to next generations. Although this idea is still hypothetical, it was interesting to see that cancer can influence human evolution.