Deletion polymorphism in the human COLIA2 gene: Genetic evidence of a non-African population whose descendants spread to all continents

We report the frequencies of a deletion polymorphism at the (alpha(2) (1) c ollagen gene (COL1A2) and argue that this distribution has major implicatio ns for understanding the evolution of modern humans immediately after their exodus from sub-Saharan Africa as well as their subsequent spread to all c ontinents. The high frequency of the deletion in non-African populations an d its complete absence in sub-Saharan African groups suggest that the delet ion event occurred just before or shortly after modem humans left Africa. T he deletion probably arose shortly after the African exodus in a group whos e descendants were among the ancestors of all contemporary populations, exc ept for sub-Saharan Africans. This, of course, does not imply that there wa s 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 thes e 2 polymorphisms suggest that the exodus from Africa may not have been a r apid dispersion to all other regions of the world. Instead, it may have inv olved a period of time for the savanna-derived gene pool to adapt to novel selective agents, such as bacteria, viruses, and/or environmental xenobioti cs found in both animal and plant foods in their new environment. In this c ontext these polymorphisms are indicators of the evolution that occurred be fore the diaspora of these populations to the current distribution of moder n peoples.