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Thread: Same age for R1a and R1b?

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    Same age for R1a and R1b?

    Question: Did the mutations that define haplogroup R1a and R1b both happen at the same time?

    In other words, do R1a and R1b necessarily have the same age? I ask because every age estimate I have seen gives the same age for both (e.g. 22,800 YA). But couldn't R1b have split off first, and the first R1a individual have appeared only much later?

    I guess the question applies equally to the split between other main haplogroups.

    Best regards,
    Jon

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    If we look
    Y-DNA Haplogroup R1 and its Subclades - 2018
    https://isogg.org/tree/ISOGG_HapgrpR.html

    R1 is a father, R1a and R1b are the sons(they should be of similar age), but how much I follow it in the past (the claims of the Anatole Klyosov if I understood well) R1a mutation should be a little bit older because it has this A (R1a)?

    I do not know if this is true and whether these letters have meaning, should be seen what the profession and scientific papers say about it (we are waiting for someone).

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    They split from R1 at the same time, but their TMRCA (time to most recent common ancestor) is different.

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    If R1a and R1b split from R1 at the same time, it seems that the two mutations that define R1a and R1b (M420 and M343 respectively) must have both happened at the same time. This seems very improbable. Don't you agree?

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    Quote Originally Posted by thejkhan View Post
    They split from R1 at the same time, but their TMRCA (time to most recent common ancestor) is different.
    If we look YFull tree and TMRCA for R1a and R1b, R1b for now has older TMRCA but it's constantly changing so we will know real age in the future.

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    Quote Originally Posted by hman View Post
    If R1a and R1b split from R1 at the same time, it seems that the two mutations that define R1a and R1b (M420 and M343 respectively) must have both happened at the same time. This seems very improbable. Don't you agree?
    If the father has two sons then they should have same father or grandfather mutation, this should be a logic. Since mutation occurs every 150 years apparently R1b and R1a are different mutations from a different time period (M420 and M343 respectively) and do not have same father or grandfather mutation which would mean that they were not created at the same time although YFull and ISOGG show this.

    Or to translate they in fact have a common ancestor R1 (father) but then his sons must either have R1a or R1b ie M420 or M343 which in fact means that their ancestor are someone behind R1 subclade or one ancestor is R1 and other someone else ( cousin of R1 ?)


    In my opinion it is because YFull for now can not detect this difference of 150 or 300 years that happened 28 thousand years ago but apparently R1a and R1b arose from same ancestor branch or ancestors (relatives) but possible in different time periods ranging from 200 to 300 or more years. Possibly in the future YFull will correct this time period of formation R1a or R1b subclade. This is my logical thinking since I'm not a geneticist.

    R1 is old 28 thousand years and R1a 22 thousand years, how is it possible when a mutation occurs every 150 years ? That why I say that detection each mutation and exact age of formation at that exact time is quite difficult.

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    Quote Originally Posted by hman View Post
    If R1a and R1b split from R1 at the same time, it seems that the two mutations that define R1a and R1b (M420 and M343 respectively) must have both happened at the same time. This seems very improbable. Don't you agree?
    While M420 and M343 may be used to refer to R1a and R1b, each of these clade is defined by multiple SNPs.

    At the time of the split, all that needed to happen is that a son of an R1 father has a new, single mutation (SNP) that defines either one of R1a or R1b. There, that is the split!

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    If we follow logic, that San people are more archaic, because they have less mutations, compared to others, then I would look at R1a and R1b in the way, that R1a is more archaical, because it stayed at home and mixed among similar people, creating lesser mutations, when R1b decided to move and mingle with others. R1a moved, too, but somewhat later and had less mutations among themselves again, because they either populated empty areas, or killed off locals, just like R1b, or mixed with similar R1b. Kinda paradox, that R1a is more archaical and fresh expansion, compared to R1b.

    Same can be applied to more archaical C spread in central Asia. It does not mean that more archaical people die out by default, if they can spread.

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    Quote Originally Posted by thejkhan View Post
    While M420 and M343 may be used to refer to R1a and R1b, each of these clade is defined by multiple SNPs.
    At the time of the split, all that needed to happen is that a son of an R1 father has a new, single mutation (SNP) that defines either one of R1a or R1b. There, that is the split!
    I understand that, but in the case you describe only R1a (or R1b) will exist, while the remaining men with haplogroup R1 will still have the same haplogroup R1. The mutation(s) necessary for starting up the R1b (or R1a) lineage will happen at a later, unknown time. Or am I missing something?

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    Quote Originally Posted by hman View Post
    I understand that, but in the case you describe only R1a (or R1b) will exist, while the remaining men with haplogroup R1 will still have the same haplogroup R1. The mutation(s) necessary for starting up the R1b (or R1a) lineage will happen at a later, unknown time. Or am I missing something?
    I see what you're saying. Basically the time to the split and the time to the formation of a particular subclade may not necessarily be the same. Having said that, there's an assumption that a mutation occurs every 144 years, so at most it would take another 144 years (or much less) for the mutation, that defines the other clade, to occur (at least theoretically). When we discuss ages as old as 28k years, +/- 144 can be ignored I guess.

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    Quote Originally Posted by thejkhan View Post
    I see what you're saying. Basically the time to the split and the time to the formation of a particular subclade may not necessarily be the same. Having said that, there's an assumption that a mutation occurs every 144 years, so at most it would take another 144 years (or much less) for the mutation, that defines the other clade, to occur (at least theoretically). When we discuss ages as old as 28k years, +/- 144 can be ignored I guess.
    This sounds reasonable, but I don't think it is that simple. Look at Y-haplogroup R, according to the estimates shown on this site it took about 4000 years from it appeared until it split into R1 and R2, and about 4000 years again until R1 split into R1a and R1b. This is why I started to think that maybe R1a and R1b don't have the same age after all. Even today there are a few people with ancient haplogroups without deep subclades, so the defining mutation for R1a (and R1b) could as I see it have happened at any time between the appearance of R1 and the first known appearance of R1a (or R1b). Although of course we don't know any of these dates exactly.

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    Quote Originally Posted by thejkhan View Post
    I see what you're saying. Basically the time to the split and the time to the formation of a particular subclade may not necessarily be the same. Having said that, there's an assumption that a mutation occurs every 144 years, so at most it would take another 144 years (or much less) for the mutation, that defines the other clade, to occur (at least theoretically). When we discuss ages as old as 28k years, +/- 144 can be ignored I guess.
    I don't think it can be that simple. According to the age estimates provided at this site, it took about 4000 years from Y-haplogroup R appeared until it split into R1 and R2, and about the same time before R1 again split into R1a and R1b. This is why I started thinking that maybe R1a and R1b may not be equally old after all.

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