ABO gene may be salient to the out of Africa migrations to the Americas

Abstract

The source populations of Native Americans lived in Asia and Eurasia some 35,000 to 40,000 years ago. Consensus is that they migrated to Beringia some 25,000 to 30,000 years ago, when the low sea levels from the Last Glacial Maximum period allowed a land bridge to form to Beringia. Subsequently, the Native American ancestors migrated south to North and South America, whereas the remaining Beringia population, Eskimos, migrated into Canada and Greenland. Genetic evidence along with anthropological research adds much to the understanding of the course of their migrations and population growth. Because present-day Native Americans are essentially all of ABO O blood type, and the other Beringia populations, the Eskimos, were polymorphic for the ABO blood groups given the extensive research revealing pleiotropy of ABO blood group alleles, this unusual population frequency distribution of ABO blood groups offers an opportunity to understand how a population with no diversity of ABO blood groups differs from one that is similar in other genes but polymorphic in ABO blood groups. ABO blood groups in migrating populations provide supporting evidence for the timelines, destinations, and cultures of those populations leaving Africa. Other genes add to the power of ABO blood groups to provide this evidence. One of those genes, in the case of Native American and Eskimo migrations, is the gene for a dental trait called shovel shaped incisors, ectodysplasin A receptor (EDAR), which is prevalent in northeast Asian populations and is fixed in Native American populations. Because of the known climatic conditions in Africa at the time of the major out-of-Africa migration periods and malaria-related climatic aspects of the selection of the ABO A2 vs ABO A1 gene, it appears that the population ratio of ABO A2 to ABO A1 and EDAR associated shovel shaped incisor frequencies is associated with the timelines of the population leaving Africa as well as their further migrations. Because Native Americans have a very high shovel shaped incisor frequency and no ABO A2, their timeline of migrating from northeast Asia and Eurasia, observed using this approach and agreeing with other lines of evidence, is supported to be 25,000–30,000 years ago. Furthermore, separation of the Beringia population into a monomorphic ABO O group, the Native Americans, and an ABO polymorphic group, the Eskimos, in light of research supporting pleiotropy of ABO alleles enhances our understanding of their respective divergent migration paths, cultures, and population growth.