关键词: DNA, 亚洲起源说, 非洲起源说, 遗传多样性上限理论, 中性理论, 分子钟

Abstract:

It was in 1983 that scientists constructed the first molecular model of modern human origin based on the mitochondrial DNA (mtDNA) phylogenetic tree, and concluded that modern people originated in Asia. However, in 1987, the Out of Africa model also known as African Eve model was proposed and replaced the original model. But the infinite site assumption and the molecular clock hypothesis on which the African Eve model was based have been widely considered to be unrealistic. In recent years, we have proposed a new molecular evolution theory, namely the maximum genetic diversity(MGD) theory, and used it to reconstruct a new model of human origin, which is basically consistent with the Multiregional model and has the root of modern humans in East Asia. The main difference between the African Eve and our Asia model in the mtDNA tree is the relationship between haplotypes N and R. The African Eve model says that N is the ancestor of R, and our model indicates it is the opposite. In this research, we studied those mtDNA data published from ancient samples, focusing on the relationship between mitochondrial haplogroup N and R. The results show that the three oldest humans (one from 45,000 years ago and the other two about 40,000 years) belong to the haplogroup R. In the human samples from 39,500 to 30,000 years ago, most of them belong to the sub-haplogroup U downstream of the haplogroup R, and only two of them fall into the haplogroup N group(Oase1 is 39,500 years ago, Salkhit is 34,426 years ago). The haplotypes of these two individuals are not part of any prensent N downstream haplotypes and so may be close to the roots of the haplogroup N. These ancient DNA data reveal that the haplogroup R is about 5,000 years older than the haplogroup N, thus confirming the East Asia model and invalidating the African Eve model.

Key words: DNA, Out of East Asia model, Mitochondrial African Eve Model, Maximum genetic diversity(MGD) theory, Neutral theory, Molecular clock