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Genetic Closeness of the East/West African SNP population clusters (blog source)
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[QUOTE]Originally posted by Dead: [QB] Statistical differences in haplogroup frequencies between populations may be the result of population structure as opposed to being considered reliable markers of phylogeny. Example: "Many proposals for haplogroup A's origin suggest it was associated with the ancestral population of Southern Africa's hunter-gatherers. This is because Haplogroup A lineages are frequent among the San people." - Wikipedia This assumption is false. Haplogroup A could have originated outside of Africa. Furthermore MtDNA and Y-DNA is not population history. Neither are (neutral) phylogenetic markers. "The vast majority of studies employing mtDNA as an evolutionary marker have not attempted to test the basic assumptions and predictions of the neutral model: a constant mutation rate, a stationary allele frequency distribution, and a correlation between polymorphism levels and divergence. The omission of these tests limits our ability to interpret the results of these analyses, but perhaps more importantly it misses an opportunity to understand the nature of selection operating on mitochondria. We suggest that [b]the focus of mitochondrial study should shift away from using mtDNA as a tool for inference of population history[/b] towards studies of the ecology and biochemistry of the mitochondrion itself." http://www.ncbi.nlm.nih.gov/pubmed/15012752 "The variation of the nonrecombining region of the Y chromosome (NRY) has been successfully used to study human origins and population histories, [b]based on the assumption that Y chromosome variation is selectively neutral[/b]." http://www.ucl.ac.uk/tcga/tcgapdf/LluisQM-JMG-03-TC.pdf This assumption for Y-DNA has shown also recently to be incorrect. As also noted you have to take into account population structure (i.e. size) when studying the frequency of a haplogroup. You cant just find it at high frequency somewhere and then claim it originated there. [/QB][/QUOTE]
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