The thing about the age estimates is that you only count SNPs that fall inside the regions where there has been work to study the rates of mutations. ?While there are 20 equivalent SNPs only 15 are used for dating the branch.
As far as the 1700 years that Elizabeth was asking about being different¡ that¡¯s in the same ballpark I¡¯m pretty sure I¡¯ve always been. ?1950 - 1700 = 250AD.
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To all:
This time/SNP thing intrigues me greatly (as I assume it does others). Let¡¯s do a little kindergarden math:
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Elizabeth notes that James has?CTS4466 formed 3,000 ybp and its¡¯ TMRCA at 1,700 ybp.
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There are 20 SNPs in the CYS4466 block making the time between forming and the TMRCA yield an average SNP rate of (3000-1700)/20 = 65 yrs/SNP.
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There are two Lee¡¯s near me who, with their 2 private variants, are some 37 SNPs below CTS4466¡¯s TMRCA. If we assume that this takes us all the way to the ¡®present¡¯, then using James¡¯s value of 1700 ybp for that time frame, we get another estimate: 1700/37 = 45.9 yrs/SNP. Of course, the two Lee¡¯s likely do not lead us up to the present; there are more SNPs to be discovered, thus making the ¡¯37¡¯ larger and the yrs/SNP smaller.
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Then if we do these together, we get 3000/57 = 52.6 yrs/SNP. And that¡¯s a max number. So 50 yrs/SNP is perhaps a better guess.
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Comments?????
¡ª joe
