Darker Skin Evolved To Reduce Cancer Risk

By Gemma Tarlach | February 26, 2014 9:43 am
A reconstruction of a female Homo erectus. reconstruction by John Gurche; photographed by Tim Evanson

A reconstruction of a female Homo erectus. Reconstruction by John Gurche; photographed by Tim Evanson

A long-discounted theory about the evolution of skin color may have had it right all along, new research suggests.

Darker skin gives individuals much greater protection from UV light-induced skin cancer. Pale-skinned people are roughly 1,000 times more likely than individuals with dark skin to suffer from the three most common skin cancers. But for years, researchers believed the lowered risk was an incidental benefit, not one derived through the pressure of natural selection.

Even Charles Darwin poo-poohed the notion that pigmentation could be an adaptive trait. A new study, however, finds evidence that skin cancer was in fact a driving evolutionary force for early hominids to have darker skin.

Skin Color and Cancer

The findings were based studying people with albinism in equatorial Africa, which has the highest UV radiation exposure on the planet. The study, based on medical records, found that more than 80 percent of people with albinism in this region developed terminal skin cancer before the age of 30, or roughly at one’s reproductive height. Thus, researchers say, individuals with light skin were likely to die sooner— and produce fewer offspring — than those with darker skin.

Researchers involved in the study believe that the earliest humans had pale skin containing pheomelanin, as do our close relatives, the chimpanzees. As our ancestors lost their body hair, likely to withstand the hot temperatures in the African savannah, that pale skin would have put them at great risk for early-onset skin cancers.

Evolution of Dark Skin

But those individuals who evolved to produce eumelanin — brown-black pigmentation — would have had a definite advantage because eumelanin affords natural protection from DNA damage — and skin cancer — caused by UV radiation. Darker-skinned early humans would have been less likely to die from skin cancer at a young age, and therefore more likely to live to produce more offspring, who would inherit their adaptive dark skin.

The study, published in Proceedings of the Royal Society B, suggests that dark skin arose between 1.2 and 1.8 million years ago in equatorial Africa — the same area where albinism so often leads to an early death from skin cancer today.

CATEGORIZED UNDER: Living World, top posts
MORE ABOUT: human origins
  • Bretzky1

    It would be an amazing coincidence indeed if the people who happen to have the darkest pigmentation to their skin just happened to live in the parts of the world with the most year-round exposure to sunlight and that such pigmentation lightened the farther one lived away from that area.

  • facefault

    Folate depletion is almost certainly a bigger reason than skin cancer.

  • DarkySatire

    It would be even more amazing if the exposure to sun in those areas is also somehow contributing to the apparently more aggressive behavior of the natives in said areas lol

    • RMR

      It doesn’t

  • Morgan Chaney

    I agree with facefault. UV destroys folate, and a deficiency of folate during pregnancy is associated with severe birth defects (e.g., spina bifida). Being predisposed to birthing deformed babies tends to have an effect on fitness.
    On another note, even early-onset skin cancer would likely occur after some successful reproduction. Folate’s the key – not cancer.

    • steve sexauer

      maybe. but children are still more likely to survive with parents, and people with elders around who accumulated more knowledge are more likely to survive, so, there was likely some selection occurring.

  • IAteLunchToday

    I haven’t really ever given it that much thought or I missed class that day, but I just kind of always thought we started out darker and then got lighter in different parts. Apparently I had it backwards. And I always thought that, of course, skin color was an adaptive trait.

  • alex

    Evolution is a big lie and deception

    • shipsternsbluff

      sure it is….but the bible is truth….what a bunch of BS

    • steve sexauer

      you are demonstrating why we should not tolerate religion.

  • Jimmy

    The truth is slowly coming out that current total sun abstinence is incorrect. It’s about time!

  • Neilos Barross

    But can’t darker skin people have Vitamin D deficiencies which is known to cause other issues including cancer?

    • mrpolyamory

      Only if they adopt Western dress and lifestyles like Western “cave people” in homes, offices and cars that shield them from the sunlight that they’d be basking in by living a more natural lifestyle. That’s why blacks in Western societies have so much more serious vitamin D deficiencies than do whites, but even most indoor-living whites are deficient. We all need to spend more time outside in the nude or mostly so.

  • mrpolyamory

    How silly. My white ancestors evolved lighter color so they could produce vitamin D in the skin utilizing the much less intense sunlight in the Northern latitudes which they gradually occupied coming out of Africa and where they had to wear more clothing for protection against the cold thus limiting vitamin D production.

  • Lisa Raffensperger

    Thanks Ronald for spotting that – it’s now been fixed.

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