title: Evolution of the pygmy phenotype: evidence of positive selection fro genome-wide scans in African, Asian, and Melanesian pygmies.
abstract: Human pygmy populations inhabit different regions of the world, from Africa to Melanesia. In Asia, short-statured populations are often referred to as "negritos." Their short stature has been interpreted as a consequence of thermoregulatory, nutritional, and/or locomotory adaptations to life in tropical forests. A more recent hypothesis proposes that their stature is the outcome of a life history trade-off in high-mortality environments, where early reproduction is favored and, consequently, early sexual maturation and early growth cessation have coevolved. Some serological evidence of deficiencies in the growth hormone/insulin-like growth factor axis have been previously associated with pygmies' short stature. Using genome-wide single-nucleotide polymorphism genotype data, we first tested whether different negrito groups living in the Philippines and Papua New Guinea are closely related and then investigated genomic signals of recent positive selection in African, Asian, and Papuan pygmy populations. We found that negritos in the Philippines and Papua New Guinea are genetically more similar to their nonpygmy neighbors than to one another and have experienced positive selection at different genes. These results indicate that geographically distant pygmy groups are likely to have evolved their short stature independently. We also found that selection on common height variants is unlikely to explain their short stature and that different genes associated with growth, thyroid function, and sexual development are under selection in different pygmy groups.
authors.affiliation: Department of Anthropology, University College London, London, UK.
authors.forename: Andrea Bamberg
authors.initials: AB
authors.lastname: Migliano
authors.forename: Irene Gallego
authors.initials: IG
authors.lastname: Romero
authors.forename: Mait
authors.initials: M
authors.lastname: Metspalu
authors.forename: Matthew
authors.initials: M
authors.lastname: Leavesley
authors.forename: Luca
authors.initials: L
authors.lastname: Pagani
authors.forename: Tiago
authors.initials: T
authors.lastname: Antao
authors.forename: Da-Wei
authors.initials: DW
authors.lastname: Huang
authors.forename: Brad T
authors.initials: BT
authors.lastname: Sherman
authors.forename: Katharine
authors.initials: K
authors.lastname: Siddle
authors.forename: Clarissa
authors.initials: C
authors.lastname: Scholes
authors.forename: Georgi
authors.initials: G
authors.lastname: Hudjashov
authors.forename: Elton
authors.initials: E
authors.lastname: Kaitokai
authors.forename: Avis
authors.initials: A
authors.lastname: Babalu
authors.forename: Maggie
authors.initials: M
authors.lastname: Belatti
authors.forename: Alex
authors.initials: A
authors.lastname: Cagan
authors.forename: Byrony
authors.initials: B
authors.lastname: Hopkinshaw
authors.forename: Colin
authors.initials: C
authors.lastname: Shaw
authors.forename: Mari
authors.initials: M
authors.lastname: Nelis
authors.forename: Ene
authors.initials: E
authors.lastname: Metspalu
authors.forename: Reedik
authors.initials: R
authors.lastname: Mägi
authors.forename: Richard A
authors.initials: RA
authors.lastname: Lempicki
authors.forename: Richard
authors.initials: R
authors.lastname: Villems
authors.forename: Marta Mirazon
authors.initials: MM
authors.lastname: Lahr
authors.forename: Toomas
authors.initials: T
authors.lastname: Kivisild
mesh_terms: D006801:Humans; D000222:Adaptation, Physiological / Q000235:genetics; D000885:Anthropology, Physical; D044466:Asian People / Q000208:ethnology / Q000235:genetics; D005075:Biological Evolution; D044383:Black People / Q000208:ethnology / Q000235:genetics; D001827:Body Height / Q000208:ethnology / Q000235:genetics; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D010219:Papua New Guinea / Q000208:ethnology; D010641:Phenotype; D010679:Philippines / Q000208:ethnology; D020641:Polymorphism, Single Nucleotide; D000095188:Pacific Island People / Q000235:genetics