title: Diet and the evolution of human amylase gene copy number variation.
abstract: Starch consumption is a prominent characteristic of agricultural societies and hunter-gatherers in arid environments. In contrast, rainforest and circum-arctic hunter-gatherers and some pastoralists consume much less starch. This behavioral variation raises the possibility that different selective pressures have acted on amylase, the enzyme responsible for starch hydrolysis. We found that copy number of the salivary amylase gene (AMY1) is correlated positively with salivary amylase protein level and that individuals from populations with high-starch diets have, on average, more AMY1 copies than those with traditionally low-starch diets. Comparisons with other loci in a subset of these populations suggest that the extent of AMY1 copy number differentiation is highly unusual. This example of positive selection on a copy number-variable gene is, to our knowledge, one of the first discovered in the human genome. Higher AMY1 copy numbers and protein levels probably improve the digestion of starchy foods and may buffer against the fitness-reducing effects of intestinal disease.
authors.affiliation: School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: George H
authors.initials: GH
authors.lastname: Perry
authors.forename: Nathaniel J
authors.initials: NJ
authors.lastname: Dominy
authors.forename: Katrina G
authors.initials: KG
authors.lastname: Claw
authors.forename: Arthur S
authors.initials: AS
authors.lastname: Lee
authors.forename: Heike
authors.initials: H
authors.lastname: Fiegler
authors.forename: Richard
authors.initials: R
authors.lastname: Redon
authors.forename: John
authors.initials: J
authors.lastname: Werner
authors.forename: Fernando A
authors.initials: FA
authors.lastname: Villanea
authors.forename: Joanna L
authors.initials: JL
authors.lastname: Mountain
authors.forename: Rajeev
authors.initials: R
authors.lastname: Misra
authors.forename: Nigel P
authors.initials: NP
authors.lastname: Carter
authors.forename: Charles
authors.initials: C
authors.lastname: Lee
authors.forename: Anne C
authors.initials: AC
authors.lastname: Stone
mesh_terms: D000818:Animals; D004032:Diet; D019143:Evolution, Molecular; D018628:Gene Dosage; D014644:Genetic Variation; D006801:Humans; D013213:Starch / Q000378:metabolism; D000516:alpha-Amylases / Q000235:genetics*