Grab the Gauge
09-30-2016, 07:29 PM
Who's your daddy?
http://www.gbe.oxfordjournals.org/content/6/3/466.full
To study the male and female lineages of East Asian and European humans, we have sequenced 25 short tandem repeat markers on 453 Y-chromosomes and collected sequences of 72 complete mitochondrial genomes to construct independent phylogenetic trees for male and female lineages. The results indicate that East Asian individuals fall into two clades, one that includes East Asian individuals only and a second that contains East Asian and European individuals. Surprisingly, the European individuals did not form an independent clade, but branched within in the East Asians. We then estimated the divergence time of the root of the European clade as ∼41,000 years ago. These data indicate that, contrary to traditional views, Europeans diverged from East Asians around that time. We also address the origin of the Ainu lineage in northern Japan.
For the male lineages, we used the Y-STR markers for 453 individuals covering Japanese, Korean, Mongolian (Khalkh), American, and European people. We determined the evolutionary distances (RST) among them, and constructed a phylogenetic tree using the NJ method (Saitou and Nei 1987), as shown in figure 1. The Y-STR tree revealed that the male ancestral lineage contained two clades (Yap-A and Yap-B). While Yap-A clade includes the East Asian individuals only, Yap-B clade contains the East Asian and European individuals together. Surprisingly, the European males never formed an independent clade. Instead, they formed separate clades within Yap-B.
We then constructed a phylogenetic tree (Mt tree) for the 72 complete mtDNAs including the four ethnic groups, as shown in figure 2. We used Kimura’s two parameter method (Kimura 1980) for computing evolutionary distances among them and the NJ method for the tree construction. The Mt tree revealed two female descendant clades (Mt A and Mt B). Mt B consisted of the East Asian females only, while Mt A contained the East Asian and European females together. As in the case of males, the European females did not form an independent clade, but comprised several groups within the Mt A tree. As the Mt A cluster includes roughly as many European individuals as East Asian individuals, it is not clear which of them is ancestral to the other. The node marked with the blue circle in figure 2 suggests that the East Asians are ancestral to the Europeans. The bootstrap value of the node is 99%. Therefore, both male and female lineages suggest that Europeans diverged from within East Asian ancestors or that they interbred with East Asian individuals up to a certain divergence time.
Our next question was thus to estimate the divergence time of the European clade within the East Asian lineage, for males and females separately. To address that question, we computed the evolutionary distance (RST) between every pair of the male individuals to construct the Y-STR tree in figure 1. The RST value between the bottom and root of A and B clades in the tree was 16.91, while that between the bottom and root of the European male clade in the B clade was 12.31. Based on a divergence of East Asians from Africans of 55,000 years ago (Nei and Roychoudhury 1974, 1993), and assuming that RST is proportional to time, we can estimate the evolutionary rate of Y-STR by using the Y-STR tree. In the tree the RST value between the deepest root and the bottom is 16.91, and that between the common ancestor of Europeans males and the bottom is 12.31. The rate is thus estimated as 16.91/55,000 = 3.07 × 10−4 per repeat per year, which leads us to the conclusion that the divergence time of the European males is ∼40,100 years ago.
http://www.gbe.oxfordjournals.org/content/6/3/466.full
To study the male and female lineages of East Asian and European humans, we have sequenced 25 short tandem repeat markers on 453 Y-chromosomes and collected sequences of 72 complete mitochondrial genomes to construct independent phylogenetic trees for male and female lineages. The results indicate that East Asian individuals fall into two clades, one that includes East Asian individuals only and a second that contains East Asian and European individuals. Surprisingly, the European individuals did not form an independent clade, but branched within in the East Asians. We then estimated the divergence time of the root of the European clade as ∼41,000 years ago. These data indicate that, contrary to traditional views, Europeans diverged from East Asians around that time. We also address the origin of the Ainu lineage in northern Japan.
For the male lineages, we used the Y-STR markers for 453 individuals covering Japanese, Korean, Mongolian (Khalkh), American, and European people. We determined the evolutionary distances (RST) among them, and constructed a phylogenetic tree using the NJ method (Saitou and Nei 1987), as shown in figure 1. The Y-STR tree revealed that the male ancestral lineage contained two clades (Yap-A and Yap-B). While Yap-A clade includes the East Asian individuals only, Yap-B clade contains the East Asian and European individuals together. Surprisingly, the European males never formed an independent clade. Instead, they formed separate clades within Yap-B.
We then constructed a phylogenetic tree (Mt tree) for the 72 complete mtDNAs including the four ethnic groups, as shown in figure 2. We used Kimura’s two parameter method (Kimura 1980) for computing evolutionary distances among them and the NJ method for the tree construction. The Mt tree revealed two female descendant clades (Mt A and Mt B). Mt B consisted of the East Asian females only, while Mt A contained the East Asian and European females together. As in the case of males, the European females did not form an independent clade, but comprised several groups within the Mt A tree. As the Mt A cluster includes roughly as many European individuals as East Asian individuals, it is not clear which of them is ancestral to the other. The node marked with the blue circle in figure 2 suggests that the East Asians are ancestral to the Europeans. The bootstrap value of the node is 99%. Therefore, both male and female lineages suggest that Europeans diverged from within East Asian ancestors or that they interbred with East Asian individuals up to a certain divergence time.
Our next question was thus to estimate the divergence time of the European clade within the East Asian lineage, for males and females separately. To address that question, we computed the evolutionary distance (RST) between every pair of the male individuals to construct the Y-STR tree in figure 1. The RST value between the bottom and root of A and B clades in the tree was 16.91, while that between the bottom and root of the European male clade in the B clade was 12.31. Based on a divergence of East Asians from Africans of 55,000 years ago (Nei and Roychoudhury 1974, 1993), and assuming that RST is proportional to time, we can estimate the evolutionary rate of Y-STR by using the Y-STR tree. In the tree the RST value between the deepest root and the bottom is 16.91, and that between the common ancestor of Europeans males and the bottom is 12.31. The rate is thus estimated as 16.91/55,000 = 3.07 × 10−4 per repeat per year, which leads us to the conclusion that the divergence time of the European males is ∼40,100 years ago.