Race and Genetics - Ancestral Populations

Ancestral Populations

A widely cited 1994 study by Cavalli-Sforza et al. evaluated the genetic distances between 42 native populations from around the world based on 120 blood polymorphisms. These 42 populations can be grouped into 9 main clusters, which Cavalli-Sforza termed African (sub-Saharan), Caucasoid (European), Caucasoid (extra-European), Northern Mongoloid (excluding Arctic populations), Northeast Asian Arctic, Southern Mongoloid (mainland and insular Southeast Asia), Pacific Islander, New Guinean and Australian, and American (Amerindian). Though the clusters evidence varying degrees of homogeneity, the 9-cluster model represents a majority (80 out of 120) of single-trait trees and is useful in demonstrating the historic phylogenetic relationship between these populations.

The largest genetic distance between any two continents is between Africa and Oceania at 0.2470. Based on physical appearance this may be counterintuitive, since Indigenous Australians and New Guineans resemble Africans with dark skin and sometimes frizzy hair. This large figure for genetic distance reflects the relatively long isolation of Australia and New Guinea since the end of the last glacial maximum when the continent was further isolated from mainland Asia due to rising sea levels. The next largest genetic distance is between Africa and the Americas at 0.2260. This is expected since the longest geographic distance by land is between Africa and South America. The shortest genetic distance at 0.0155 is between European Caucasoids and Non-European Caucasoids. Africa is the most genetically divergent continent, with all other groups being more related to each other than to Sub-Saharan Africans. This is expected in accordance with the recent single-origin hypothesis. Europe has a genetic variation in general about three times less than that of other continents, and the genetic contribution of Asia and Africa to Europe is thought to be 2/3 and 1/3 respectively.

Many more recent worldwide studies have also been published. Often they use an increasing number of genetic markers. Many studies have also been done on more limited regions, (one example being studies on the genetic history of Europe), or on individual nations (one example being studies on the genetic history of Italy), or on specific groups (one example being genetic studies on Jews).