A paper published in December 2019 (Early replacement of West Eurasian male Y chromosomes from the east. Pille Hallast, Anastasia Agdzhoyan, Oleg Balanovsky, Yali Xue, Chris Tyler-Smith bioRxiv 867317; doi: https://doi.org/10.1101/867317) suggested that the Y chromosome of ALL non-Africans was replaced by lineages that originated in East Asia!
Published in bioRxiv it hasn't been peer reviewed and can be read in full. The summary of this idea is given in the abstract:
"phylogenetic analyses of haplogroup C, D and FT sequences, including very rare deep-rooting lineages, together with phylogeographic analyses of ancient and present-day non-African Y-chromosomes, all point to East/South-east Asia as the origin 50,000-55,000 years ago of all known non-African male lineages (apart from recent migrants). This implies that the initial Y lineages in populations between Africa and eastern Asia have been entirely replaced by lineages from the east, contrasting with the expectations of the serial-founder model."
So, this paper says that instead of splitting into different haplotypes close to Africa, say in the Middle East after leaving it, human Y-chromosomes began diversifying in Eastern Asia. Then these haplogroups replaced any others that may have appeared to the west of them.
Below is the map shown in this paper's Figure 3, mentioned in the following quote from the same paper.
"In a simple model of gradual human expansion from Africa to Asia and Oceania without subsequent continental-scale reshaping, we would expect the initial divergences in the Y-chromosomal phylogeny to have occurred in geographical locations close to Africa, and the present-day Y-chromosomal phylogeography to reflect this history by showing the presence of the early-diverging lineages within C, D and FT now being located geographically in Central/West Asia (Figure 3a). In stark contrast, the observed distributions of these lineages all lie further to the East, suggesting that their early divergences occurred in the East...
How then can the present-day Y-chromosomal phylogeography be reconciled with an out-of-Africa expansion? The simplest explanation is that initial western Y chromosomes have been entirely replaced by lineages from further east, perhaps on more than one occasion. "
Interesting version of an "Out of China" theory. Yet, it retains the original notion of H. sapiens leaving Africa and originating there.
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