In today’s Academic Minute, Dr. Nina Jablonski of Penn State University explains how evolution has created such broad spectrum of human skin color.
Nina Jablonski is Distinguished Professor of Anthropology at Penn State University. As a biological anthropologist and paleobiologist, she studies the evolution of environmental adaptations in Old World primates including humans. Her research into human evolution centers on the shift of human skin and skin pigmentation, and includes an active field project examining the relationship between skin pigmentation and vitamin D production. She holds a Ph.D. from the University of Washington and in 2012 she published, Living Color: The Biological and Social Meaning of Skin Color.
Dr. Nina Jablonski – Evolution and Skin Color
I study human evolution, and my special interest is in skin and skin color. We Homo sapiens evolved in Africa around 200,000 years ago and had darkly pigmented skin that was well-adapted to strong sunlight and high levels of ultraviolet radiation. Around 70,000 years ago, small groups left Africa and spread into Asia and Europe. These people eventually evolved depigmented skin by natural selection. Lighter skin made it easier for vitamin D to be produced in skin under conditions of weaker and more seasonal sunlight. By about 5000 years ago, sunnier places were populated by more darkly pigmented people and places with weaker sun were inhabited by more lightly pigmented people.
This situation changed dramatically as people began to move over long distances at fast speeds, and has sped up considerably in the last 500 years. Many people today live far away from their ancestral homelands, and their skin color doesn’t match the solar conditions under which they live. These mismatches create some serious health problems. People with light skin who live in sunny places are more likely to get skin cancer, and people with dark skin living in far northern or southern latitudes are more likely to be deficient in vitamin D. The most serious mismatch is related to urban living. Regardless of skin color, city dwellers are more likely to be deficient in vitamin D because they spend most of their time indoors and don’t have enough vitamin D in their diets. Vitamin D is important for health, and we need to make sure that get enough of the “sunshine vitamin” even if we don’t get very much sunshine.