Ann Gibbons has a very nice profile of biological anthropologist Nina Jablonski in last week’s Science: “Shedding light on skin color”. Jablonski is well-known as an expert in the paleontology of Old World monkeys, and starting more than twenty years ago began to investigate the evolutionary background of skin, hair and eye pigmentation in human populations around the world.
Gibbons reviews this research, including Jablonski’s proposal that the selective value of dark pigmentation lies mostly in preventing folate destruction by ultraviolet light in the skin, instead of skin cancer or other causes.
Some of Jablonski's ideas remain unproven. Yet her work is injecting a shot of evolutionary perspective into medicine and influencing researchers to test how sunlight affects health. Jablonski has “opened my eyes to so many things I hadn't thought about,” says perinatal epidemiologist Lisa Bodnar of the University of Pittsburgh in Pennsylvania. Radiation epidemiologist Michael Kimlin of the Queensland University of Technology in Brisbane, Australia, agrees. “We have this brand-new field in which people are suggesting that when we put our bodies in the sun, there are complex interactions,” he says. “What Nina's doing is not only contributing to evolutionary science … she's creating ripples in [biomedical] science and giving people like me hypotheses to test.”
I found that quote interesting because it really is illustrative of the thought mold in biomedical research circles. Thinking about human biology in an evolutionary framework really can lead to new (and sometimes unexpected) insights, but only a small proportion of medical researchers have any background or interest in evolutionary biology. I’ve worked with a number of such researchers and hope to do so more in the future.
The study of pigmentation is one of the topics of classic physical anthropology, but only now are we beginning to understand that pigmentation variation is diverse in its origins, most of which are surprisingly recent. Many of the genes that influence human variation in pigmentation have been subject to strong natural selection during the last 20,000 years; others have variation that has come in from archaic human populations. This is a rapidly changing story in human evolution.
Jablonski’s book, Skin: A Natural History is an account of the biology of skin in humans, touching on not only pigmentation but also other uniquely human aspects such as sweating.