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[QUOTE]Originally posted by Ish Gebor: [QB] [QUOTE]Originally posted by capra: [qb] [QUOTE]Originally posted by Ish Gebor: [qb] So why did they change it into T1a, T1a-M70 and K2-M526? It's a serious question.[/qb][/QUOTE]Well Karafet changed K2 to T in 2008, and everyone went along with her, but she didn't explain why. I guess she just figured all the K names were getting confusing and we should use some of the leftover letters. When they found that some men had the M184 and L206 mutations but not the M70 mutation - previously all of these were considered equivalent markers for haplogroup T - that showed that M70 marked a subclade of T, so they renamed it T1-M70, a branch of T-M184. Later they found that some men had M184 but not L206, so they made a new level, T1-L206, and demoted M70 to T1a. (You can look at the ISOGG trees for previous years and see the changes from year to year.) When they found that L and T were on one branch of K (sharing the mutation P326) and that M, N, O, P, and S were on another (sharing M526), these branches were named K1 and K2. This is the main reason the nomenclature changes, they keep finding new levels of branching in the tree (this is why R1b1a changed to R1b1a2, they found the L754 level). Sometimes though people just propose changes because they think it's clearer, and it may catch on or it may not. There's no fixed standard that everyone adheres to, usually people go by ISOGG but there is also a different one introduced by Karmin et al that some people are using. This is why it is always good to include the mutation name, say K2-M70 instead of just K2, because if you say K2 what did you mean? And even using the latest terms when someone comes back and reads it again in five years it'll probably have changed again. [/qb][/QUOTE]Thanks, this explains a lot, [i]"but she didn't explain why".[/i] And yeah, I did look up ISOGG. What it tells me is that a lot findings are undefined and actually uncertain, but are constantly being centered on an idea / ideal, thus the hypothesis. Brenna Henn, in this 2014 interview on population genetics and population structure, considering African populations. [b]“African populations have the most genetic diversity in the world,” Henn said.“[/b] If you compared people from the Kalahari Desert to people from Mali, they’d be as different from each other [genetically] as Italians and Chinese people.” Why are other populations of humans so much less genetically varied than Africans? The answer, Henn explains, lies in our ancestors’ history; the groups of people that migrated out of Africa and spread throughout other continents were smaller subsets of that original, genetically diverse population. Brenna Henn: [b]”AND WITHIN EACH OF THESE GROUPS THERE IS AN AMAZING AMOUNT OF DIVERSITY, […] THE DIVERSITY IS INDIGENOUS TO AFRICAN POPULATIONS”[/b]: Tracing Family Trees, And Human History, With Genetics http://youtu.be/Pjf0qKdzmrc [QUOTE]"however, the time and the extent of genetic divergence between populations north and south of the Sahara remain poorly understood"[/QUOTE]--Brenna Henn Published: January 12, 2012DOI: 10.1371/journal.pgen.1002397: "Genomic Ancestry of North Africans Supports Back-to-Africa Migrations" [QUOTE] [b]Human genetic variation particularly in Africa is still poorly understood. [/b] This is despite a consensus on the large African effective population size compared to populations from other continents. Based on sequencing of the mitochondrial Cytochrome C Oxidase subunit II (MT-CO2), and genome wide microsatellite data we observe evidence suggesting the effective size (Ne) of humans to be larger than the current estimates, with a foci of increased genetic diversity in east Africa, and a population size of east Africans being at least 2-6 fold larger than other populations. Both phylogenetic and network analysis indicate that east Africans possess more ancestral lineages in comparison to various continental populations placing them at the root of the human evolutionary tree. Our results also affirm east Africa as the likely spot from which migration towards Asia has taken place. The study reflects the spectacular level of sequence variation within east Africans in comparison to the global sample, and appeals for further studies that may contribute towards filling the existing gaps in the database. The implication of these data to current genomic research, as well as the need to carry out defined studies of human genetic variation that includes more African populations; particularly east Africans is paramount.[/QUOTE]--Jibril Hirbo, Sara Tishkoff et al. The Episode of Genetic Drift Defining the Migration of Humans out of Africa Is Derived from a Large East African Population Size PLoS One. 2014; 9(5): e97674. Published online 2014 May 20. doi: 10.1371/journal.pone.0097674 [/QB][/QUOTE]
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