for National Geographic News
Tuberculosis may have infected human ancestors much earlier than previously thought, according to scientists who have discovered traces of the disease in a hominin fossil about 500,000 years old.
Researchers say the findings could provide a better understanding of the roles of climate, health, and evolution in ancient human migration.
The fossilized Homo erectus, an extinct branch of early human ancestors, was discovered in a block of travertine rock mined from a quarry near Kocabas in western Turkey.
Based on the shape of the skull and large ridges of the brow, scientists think the remains belong to a male between 15 and 40 years of age. But they also found something else.
"There were widespread little lesions on the inside of the skull," said John Kappelman, an anthropologist at the University of Texas, Austin.
"Those lesions are distinctive of a specific kind of tuberculosis that infects the meninges, or membranes that surround the brain," he added.
During such an infection, inflamed nodules within the membranes create pressure on the bone surface, leaving the lesions.
Kappelman's findings appear in today's issue of the American Journal of Physical Anthropology.
Vitamins and Skin Color
The findings offer insight into how vitamin D might have played a crucial role in early human migration.
Vitamin D is synthesized in the skin by exposure to sunlight. Since ultraviolet radiation penetrates only the top layers of skin, people with darker complexions produce less of the vitamin, as the pigment in their skin filters out the light.
Previous studies have suggested that humans migrating north developed a lighter skin complexion as an adaptive response to maintain their vitamin D levels when exposed to less sunlight.
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