Variation in modern human incisor shoveling has been associated with the presence/absence of the V370A allele of the Ectodysplasin A Receptor ( EDAR) gene. The morphology of Neanderthal's anterior teeth has been seen as an adaptation to the heavy use of their canines and incisors in processing and chewing food, and the use of their teeth for activities other than feeding. Shovel-shaped dental characteristic are also observed in Homo erectus like the Peking Man and in Neanderthals, although the morphology of these shoveled incisors is distinct from the modern human form of shoveling. Similarly, the grades for both shovel-shaped incisors and the double shovel-shaped incisors in females are significantly greater than that in males. Structurally resembling the shovel-shaped incisors, double-shovel-shaped incisors are distinguished by a more pronounced mesial ridge comparing to the distal ridge. When present, shovel-shaped incisors can indicate correlation among populations and are considered to be one of the non-metrical traits in osteology. In some instances, incisors can present a more pronounced version of this called double shovel-shaped. However, more modern research suggests that instead genetics plays a role in the degree of shoveled-ness. It was theorized that positive selection for shovel shaped incisors over the spatulate incisors are more commonly found in anthropoids within cultures that used their teeth as tools due to a greater structural strength in increased shovel shaped incisors. There is a spectrum of the degree of shoveled-ness, ranging on a scale from 0 to 7 of spatulate incisors to shoveled incisors. In European and African groups, shovel-shaped upper incisors are uncommon or not present. They are also common in East and Central Asians, Hungarians, the Inuit and Aleut peoples of Northeast Asia and North America (including but not limited to the Inuit peoples of eastern Alaska, arctic Canada and Greenland). Shovel-shaped incisors are significantly common in Amerindians from North, Central and South America. Shovel-shaped incisors and Non Shovel-shaped incisors.
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