Variation in modern human<unk> unk> ing has been associated with the presence/absence of the V370A allele of the Ectodysplasin A Receptor (EDAR) gene. The EDAR V370A isoform arises from a single nucleotide polymorphism/missense mutation which changes the 370 Valine residue to an Alanine on the EDAR gene. The effect is approximately additive, where individuals with one copy of the allele have intermediate expression of<unk>  and homozygotes have more strongly<unk> ed<unk> . The trait is pleiotropically related to thicker and straighter hair shafts, other dental traits, sweat glands, and mammary gland ductal branching. An earlier quantitative genetic analysis of a Finnish population also revealed that inheritance of<unk> unk> ing is monogenic. The 1540C allele of EDAR is also strongly correlated with the presence of<unk>  and hair thickness, as found in a study conducted on the DNA from Japanese populations. People with Amerindian or East Asian ancestry have thicker and straighter hair. High quality replica of the right upper central<unk> teeth of a Middle Pleistocene hominin. It is hypothesized that other pleiotropic effects associated with the V370A allele were favored by natural selection to help promote the presence of the allele and thus the emergence of<unk> . One of these associated traits is increased ductal branching in the mammary gland, which improves nutrient transport in breastmilk. This may likely have conferred a survival advantage to those with the allele during the Last Glacial Maximum in certain environments with high altitudes and low Vitamin D.
Shovel-shaped incisors
Chattering teeth
Spotted lunulae
High-arched palate
Elfin facies
Maxillary hypoplasia
Condylar hypoplasia
Hippocratic facies