EDAR and other genes provide instructions for making proteins that work together during embryonic development. These proteins form part of a signaling pathway that is critical for the interaction between two cell layers, the ectoderm and the mesoderm. In the early embryo, these cell layers form the basis for many of the body's organs and tissues. Ectoderm-mesoderm interactions are essential for the proper formation of several structures that arise from the ectoderm, including the skin, hair, nails, teeth, and sweat glands.
A derived G-allele point mutation (SNP) with pleiotropic effects in EDAR, 370A or rs3827760, found in most modern East Asians and Native Americans but not common in African or European populations, is thought to be one of the key genes responsible for a number of differences between these populations, including the thicker hair, more numerous sweat glands, smaller breasts, and the Sinodont dentition (so-called shovel incisors) characteristic of East Asians. It has been hypothesized that natural selection favored this allele because it increased Vitamin D production in breast milk in populations in the far north. The 370A mutation arose in humans approximately 30,000 years ago, and now is found in 93% of Han Chinese and in the majority of people in nearby Asian populations. This mutation is also implicated in ear morphology differences and reduced chin protusion. The derived G-allele is a mutation of the ancestral A-allele, the version found in most modern non-East Asian and non-Native American populations.
In a 2015 study, three (of six) ancient DNA samples (7,900-7,500 BP) from Motala, Sweden; two (3300–3000 BC) from the Afanasevo culture and one (400–200 BC) Scythian sample were found to carry the rs3827760 mutation.
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