Diet and the evolution of human amylase gene copy number variation.

• Main Authors: George H Perry, Nathaniel J Dominy, Katrina G Claw, Arthur S Lee, Heike Fiegler, Richard Redon, John Werner, Fernando A Villanea, Joanna L Mountain, Rajeev Misra, Nigel P Carter, Charles Lee, Anne C Stone, Dr Nathaniel J Dominy, Nat Genet, Author
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2007
• Subjects: Arctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1071.3857; http://www.naturaleater.com/Science-articles/Diet-amylase-gene.pdf

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 1-3 . This behavioral variation raises the possibility that different selective pressures have acted on amylase, the enzyme responsible for starch hydrolysis 4 . We found that salivary amylase gene (AMY1) copy number is correlated positively with salivary amylase protein levels, 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 level of AMY1 copy number differentiation is unusual. This example of positive selection on a copy number variable gene is one of the first in the human genome. Higher AMY1 copy numbers and protein levels likely improve the digestion of starchy foods, and may buffer against the fitness-reducing effects of intestinal disease. Hominin evolution is characterized by significant dietary shifts, facilitated in part by the development of stone tool technology, the control of fire, and most recently the domestication of plants and animals 5-7 . Starch, for instance, has become an increasingly prominent component of the human diet, particularly among agricultural societies 8 . It stands to reason, therefore, that studies of the evolution of amylase in humans and our close primate relatives may provide insight into our ecological history. Because the human salivary amylase gene (AMY1) shows extensive variation in copy number 9,10 , we first assess whether a functional relationship exists between AMY1 copy number and the level of amylase protein expression in