BERKELEY, CALIFORNIA—A genetic mutation linked to shovel-shaped incisors may have had a more consequential impact on breastfeeding, according to a report in Science Magazine. Researchers led by Leslea Hlusko of the University of California-Berkeley suggest a genetic mutation that became prevalent among the ancestors of Native Americans some 20,000 years ago may have helped them survive the dark, cold Arctic climate of Beringia by enhancing mothers’ milk ducts and increasing the amount of fat and vitamin D passed to infants. This gene is also linked to growth of thicker hair, increased development of sweat glands, and the shift to shovel-shaped incisors. The gene mutation is thought to have first occurred some 30,000 years ago in China, which had a hot, humid climate, leading researchers to speculate that the increased sweat glands offered a particular advantage. Hlusko says the shovel-shaped incisors seen in both East Asians and Native Americans were incidental to the benefits brought by natural selection through the sweat glands and improved infant nutrition. It had been previously thought that the shovel-shaped incisors themselves provided some sort of benefit to early Native Americans since their presence was widespread in known populations. For more, go to “Naia—the 13,000-Year-Old Native American.”
