title: Evolution of lactase persistence: an example of human niche construction.
abstract: Niche construction is the process by which organisms construct important components of their local environment in ways that introduce novel selection pressures. Lactase persistence is one of the clearest examples of niche construction in humans. Lactase is the enzyme responsible for the digestion of the milk sugar lactose and its production decreases after the weaning phase in most mammals, including most humans. Some humans, however, continue to produce lactase throughout adulthood, a trait known as lactase persistence. In European populations, a single mutation (-13910*T) explains the distribution of the phenotype, whereas several mutations are associated with it in Africa and the Middle East. Current estimates for the age of lactase persistence-associated alleles bracket those for the origins of animal domestication and the culturally transmitted practice of dairying. We report new data on the distribution of -13910*T and summarize genetic studies on the diversity of lactase persistence worldwide. We review relevant archaeological data and describe three simulation studies that have shed light on the evolution of this trait in Europe. These studies illustrate how genetic and archaeological information can be integrated to bring new insights to the origins and spread of lactase persistence. Finally, we discuss possible improvements to these models.
authors.affiliation: Research Department of Genetics, Evolution and Environment, University College London, Wolfson House, 4 Stephenson Way, London NW1 2HE, UK. p.gerbault@ucl.ac.uk
authors.forename: Pascale
authors.initials: P
authors.lastname: Gerbault
authors.forename: Anke
authors.initials: A
authors.lastname: Liebert
authors.forename: Yuval
authors.initials: Y
authors.lastname: Itan
authors.forename: Adam
authors.initials: A
authors.lastname: Powell
authors.forename: Mathias
authors.initials: M
authors.lastname: Currat
authors.forename: Joachim
authors.initials: J
authors.lastname: Burger
authors.forename: Dallas M
authors.initials: DM
authors.lastname: Swallow
authors.forename: Mark G
authors.initials: MG
authors.lastname: Thomas
mesh_terms: D000328:Adult; D000349:Africa; D000818:Animals; D001208:Asia; D005075:Biological Evolution; D002417:Cattle; D003198:Computer Simulation; D003612:Dairying; D005060:Europe; D015971:Gene Expression Regulation, Enzymologic; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D006801:Humans; D043322:Lactase / Q000235:genetics* / Q000378:metabolism; D007785:Lactose / Q000737:chemistry / Q000378:metabolism; D008892:Milk / Q000737:chemistry
chemical_list: D043322:Lactase; D007785:Lactose