title: Deletion polymorphism in the human COL1A2 gene: genetic evidence of a non-African population whose descendants spread to all continents.
abstract: We report the frequencies of a deletion polymorphism at the alpha 2 (1) collagen gene (COL1A2) and argue that this distribution has major implications for understanding the evolution of modern humans immediately after their exodus from sub-Saharan Africa as well as their subsequent spread to all continents. The high frequency of the deletion in non-African populations and its complete absence in sub-Saharan African groups suggest that the deletion event occurred just before or shortly after modern humans left Africa. The deletion probably arose shortly after the African exodus in a group whose descendants were among the ancestors of all contemporary populations, except for sub-Saharan Africans. This, of course, does not imply that there was a single migration out of Africa. The GM immunoglobulin haplotype GM*A,X G displays a similar distribution to that for the COL1A2 deletion, and these 2 polymorphisms suggest that the exodus from Africa may not have been a rapid dispersion to all other regions of the world. Instead, it may have involved a period of time for the savanna-derived gene pool to adapt to novel selective agents, such as bacteria, viruses, and/or environmental xenobiotics found in both animal and plant foods in their new environment. In this context these polymorphisms are indicators of the evolution that occurred before the diaspora of these populations to the current distribution of modern peoples.
authors.affiliation: Department of Genetics and Human Variation, La Trobe University, Bundoora, Victoria, Australia.
authors.forename: R J
authors.initials: RJ
authors.lastname: Mitchell
authors.forename: S
authors.initials: S
authors.lastname: Howlett
authors.forename: N G
authors.initials: NG
authors.lastname: White
authors.forename: L
authors.initials: L
authors.lastname: Federle
authors.forename: S S
authors.initials: SS
authors.lastname: Papiha
authors.forename: I
authors.initials: I
authors.lastname: Briceno
authors.forename: J
authors.initials: J
authors.lastname: Mc Comb
authors.forename: M S
authors.initials: MS
authors.lastname: Schanfield
authors.forename: C
authors.initials: C
authors.lastname: Tyler-Smith
authors.forename: L
authors.initials: L
authors.lastname: Osipova
authors.forename: G
authors.initials: G
authors.lastname: Livshits
authors.forename: M H
authors.initials: MH
authors.lastname: Crawford
mesh_terms: D017954:Africa South of the Sahara; D000818:Animals; D005075:Biological Evolution; D002874:Chromosome Mapping; D003094:Collagen / Q000235:genetics*; D004641:Emigration and Immigration; D005006:Ethnicity / Q000235:genetics; D017353:Gene Deletion; D005787:Gene Frequency / Q000235:genetics*; D005788:Gene Pool; D005819:Genetic Markers / Q000235:genetics*; D005838:Genotype; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D007129:Immunoglobulin Gm Allotypes / Q000235:genetics; D011110:Polymorphism, Genetic / Q000235:genetics*; D011323:Primates / Q000235:genetics; D012641:Selection, Genetic
chemical_list: D005819:Genetic Markers; D007129:Immunoglobulin Gm Allotypes; D003094:Collagen