关键词: 智人, 多地区演化, 最近非洲起源, 系统谱系, 穿梭扩散模型

Abstract:

Anatomically modern human (AMH) is a term used for living and fossil humans that have globular skull, short and flat face, gracile skeleton, and a set of other osteological distinctive features different from most of the archaic humans. Researchers, who take Multiregional Evolution model (MEM) as their paradigm, use AMH as a counter part of archaic Homo sapiens, while Recent African Origin (RAO) supporters use the term for all H. sapiens. MEM was derived from continuous evolution ideology. Branching evolution was believed to be negligible during the rise of modern populations. The similarities between different local populations were regarded as the results of convergent evolution. RAO on the other hand suggests that human evolution follows the cladistic form as in the other creatures. AMHs belong to a monophyletic group and have a single origin in Africa. Non-African human populations dispersed out of Africa. Archaic human populations in Europe and Asia were replaced by the anatomically modern human during the dispersal of the latter, and there were very limited genetic exchanges between modern and archaic human populations. Recent advances in ancient DNA and proteomic researches revealed that inter-specific interbreeding did occur among H. sapiens, H. neanderthalensis and the unnamed Denisovan populations. Genomic analyses, however, indicate that regions with a high frequency of Neanderthal derived alleles in modern human genomes are mostly related to deleterious genes. Strong reproductive isolation between modern humans and Neanderthals was also detected. Instead of supporting the multiregional model, the molecular data actually reveals that modern humans, Neanderthals and Denisovans are all belong to their own species at genetic level. Debates over taxonomic assignments of some specific fossils may not be helpful for detecting the evolutionary pattern of Homo in general and the origin of H. sapiens in particular, because most of recent comparisons and analyses are at specimen or population levels, not at species level. Our recent parsimony analyses and Bayesian inferring based on large data matrix revealed that the AMHs formed a monophyletic group. Another monophyletic clade represented by Dali and Harbin skulls is the sister of this group. The divergent time between Neanderthals and AMHs is over 1 million years. This estimation is much older than previous aDNA inferring, but is consistent with the recent results based on genome-wide genealogical analyses. Biogeographic model tests also reveal that a model including multiple multi-directional dispersals among Asia, Europe and Asia statistically fits the phylogenetic tree better than the MEM and RAO.

Key words: Homo sapiens, Multiregional Evolution, Recent African Origin, Phylogeny, Shuttle dispersal model