the measured skin color of indigenous human populations relative to levels of ultraviolet radiation at the earth's surface as measured by the NASA TOMS 7 satellite. In their paper on the evolution of human skin pigmentation, Jablonski and Chaplin also posited that dark skin with sweat glands evolved with the loss of most body hair, and demonstrated that sexual dimorphism in skin color was nearly universal in humans (with females tending towards lighter skin than males). They also speculated that similar skin colors evolved independently in different human populations under similar solar regimes, an insight that preceded the molecular genetic studies that confirmed the phenomenon. Jablonski's major findings explain that the physiological purpose for the variation in skin color around the world is due to the balance between the need to protect against ultraviolet radiation and facilitating the production of vitamin D. Darker skin due to increased eumelanin levels occurs in populations closer to the equator where ultraviolet radiation poses risks of folate damage, and depigmentation occurs in areas with low and highly seasonal levels of ultraviolet radiation so that vitamin D biosynthesis is not inhibited. Jablonski's recent collaboration with physiologists W. Larry Kenney and Tony Wolf at Penn State has yielded new research indicating a probable link between UV-induced folate loss and impaired thermoregulation. Jablonski has taken this connection and applied it to understanding the effects of modern lifestyles on human health. Jablonski connects certain diseases and health risks to people living in areas distant from those of their ancestors and to people who are living the modern indoors lifestyle. Vitamin D deficiency is linked directly to several serious diseases including rickets, and is implicated in the causality of multiple sclerosis and many malignancies. The main health problems related to too much UV radiation are skin cancers, the most serious and rare being cutaneous malignant melanoma. Birth defects due to folate deficiency are well known, but those tied directly to the effects of UVR-induced folate loss have not been documented in modern people. Skin color and concepts of race Since 2010, Jablonski has focused much of her research on understanding the link between skin color and the creation of color-based races during the European Enlightenment. The naming of groups of people, later referred to as races, based on skin color has proven durable because of its reinforcement by European and American business interests and politicians of the 18th century