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  • Oldest to newest genetic populations

    I was watching the national geographic cd on the origins of mankind but there is part I fail to grasp genetically.
    Here I speaking of the first wave of people out of Africa. To simplify my question let's use A for African, B for Australian bushman and SI for southern India.He makes the claim that A is first,B is second and SI is a missing link (genetically)
    Does he believe this because he finds A markers followed by B markers followed by SI markers in some of the markers he looked at in SI?
    To extend the question do we all have A markers followed by other markers depending on what wave or what route we took out of africa? Or is it more complex than that?

  • #2
    Originally posted by Brunetmj View Post
    I was watching the national geographic cd on the origins of mankind but there is part I fail to grasp genetically.
    Here I speaking of the first wave of people out of Africa. To simplify my question let's use A for African, B for Australian bushman and SI for southern India.He makes the claim that A is first,B is second and SI is a missing link (genetically)
    Does he believe this because he finds A markers followed by B markers followed by SI markers in some of the markers he looked at in SI?
    To extend the question do we all have A markers followed by other markers depending on what wave or what route we took out of africa? Or is it more complex than that?
    One way to think about this is that the ancestral, older population has greater genetic diversity.

    A: greatest genetic diversity (Africans)
    SI: Southern India
    B. Australian aborigine


    A > B (genetic diversity)
    A > SI (genetic diversity)

    In ydna research, likewise, the region of greatest diversity is more likely to be the area where the haplogroup originated.

    EDIT:
    In that documentary, Wells found that y chromosome markers exhibited the greatest diviersity in Africa, and that all Aborigines in Australia could be traced to a migration along the coast of India from African to Australia.

    example paper: http://www.ncbi.nlm.nih.gov/pubmed/17496137
    migration route: http://www.ncbi.nlm.nih.gov/pmc/arti...570/figure/F1/
    Last edited by jloe; 20th February 2011, 01:51 PM.

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    • #3
      Originally posted by Brunetmj View Post
      Does he believe this because he finds A markers followed by B markers followed by SI markers in some of the markers he looked at in SI?
      To extend the question do we all have A markers followed by other markers depending on what wave or what route we took out of africa? Or is it more complex than that?
      The order should be:
      1. Africans (A)
      2. Southern Indians (SI)
      3. Australians (natives) (B)

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      • #4
        Thanks everyone. Well it becomes apparent that I have a lot more reading to do before i understand this.
        An older group would have more mutations along
        it's DNA sequence than a younger group. This makes sense to me in determineing older and younger.What I am failing to grasp is branching.
        How it can be shown one group came from another branch. So A was first , SI was second and B third as far as more ancient to less ancient. But how do we know one came from the other?
        Perhaps a link to more reading would be helpful rather than explaining here?

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        • #5
          Originally posted by Brunetmj View Post
          Perhaps a link to more reading would be helpful rather than explaining here?
          Here's the y-dna tree: http://en.wikipedia.org/wiki/Human_Y...oups#Tree_view

          Haplogroups A and B are primarily found in Africa, whereas younger branches of the ydna are found throughout the world.
          [edit: of course, modern descendants of slaves or emigrants out of Africa could be members of ydna Haplogroups A or B and be found throughout the world and in those areas in which there was African emigration in modern times.]
          Last edited by jloe; 20th February 2011, 05:41 PM.

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          • #6
            Another way of thinking about this is as an evolutionary tree. The root of the tree can be determined thru phylogenetic software that solves to find the most reasonable, i.e. simplest tree, consistent with the known mutations.

            There are a number of software packages that are used for this.


            http://en.wikipedia.org/wiki/Phylogenetic_tree

            The y-dna haplogroup tree is based on SNPs (single-nucleotide polymorphisms), which are unique mutations
            in the dna sequence of the y chromosome. The y-dna tree is the simplest tree consistent with those mutations.
            Last edited by jloe; 20th February 2011, 06:55 PM.

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            • #7
              HTML Code:
              Haplogroups A and B are primarily found in Africa
              I guess in my first post I assumed that some evidence of A or B would be found in my European DNA . I guess I assuming now , based on the answers here, is the following:
              According to theory central Asia shows more diversity ( more mutations) than what is found in Europe). Consequently according to this theory Europeans came from Central Asia because CA is more ancient than what is found in Europe and haplogroup A and B are older than CA. Is this how the theory works?

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              • #8
                Originally posted by Brunetmj View Post
                HTML Code:
                Haplogroups A and B are primarily found in Africa
                I guess in my first post I assumed that some evidence of A or B would be found in my European DNA . I guess I assuming now , based on the answers here, is the following:
                According to theory central Asia shows more diversity ( more mutations) than what is found in Europe). Consequently according to this theory Europeans came from Central Asia because CA is more ancient than what is found in Europe and haplogroup A and B are older than CA. Is this how the theory works?
                Wherever a haplogroup is most diverse is generally more likely to be its point of origin. However, debates about the origins of some haplogroups are contentious; R1b, for example was thought to be older in older papers, but is now thought to have a more recent origin.

                Essentially, the origin of European haplogroups probably was partially from Central Asia and partially from the Near East. Anatolia is also a good candidate region for European haplogroups, as well.

                Europe was largely depopulated by the previous Ice Age, with people taking refuge in modern day Iberia, Italy, Anatolia, and the Ukraine. Once the ice sheets receded, the rest of Europe was repopulated by people from those regions as well as the Middle East and Central Asia.

                An older theory that Iberia was a primary source for the population of Western Europe has been discredited.
                Last edited by jloe; 20th February 2011, 07:08 PM.

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                • #9
                  Originally posted by Brunetmj View Post
                  HTML Code:
                  Haplogroups A and B are primarily found in Africa
                  According to theory central Asia shows more diversity ( more mutations) than what is found in Europe). Consequently according to this theory Europeans came from Central Asia because CA is more ancient than what is found in Europe and haplogroup A and B are older than CA. Is this how the theory works?
                  Here's an animation of currently accepted migrations:
                  http://www.bradshawfoundation.com/journey/

                  [his animation shows repopulation from Iberia, which is not considered as significant today]
                  Last edited by jloe; 20th February 2011, 07:38 PM.

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                  • #10
                    Ok so much to think about. Based on other answers let me see if my understanding is correct. Really I am interested in the general principle.
                    Don't get me wrong those specifics are very interesting but I am taking this one step at a time.
                    So let me try this:
                    Each haplotype has a distinct sequence of the ACTG business. But based on the number of mutations their place in world time line can be determined with an educated guess. Then with collaborating archeological evidence it could establish who was where first.So using my example above people from Central Asia have a different haplotype ,sequence of ACTG, but older than what is found in Europe ( based on more mutations), this combined with cave paintings in France ( archeology evidence) makes the inference people from France came from Central Asia . Is this more or less how the theory works?

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                    • #11
                      The phylogenetic tree is the simplest fit to the data.

                      So, the current model is that humans left Africa about 50,000 -60,000 years ago, and then proceeded to migrate to South Asia, Central Asia, etc. The precise age of individual haplogroups is not exact; there is a confidence interval in determining the age of a particular haplogroup.

                      One model consistent with the data is that some European haplogroups originated in Central Asia and repopulated Europe after the last Ice Age. The part to be careful about is assigning a particular piece of archaeology to a particular haplogroup. It's not necessarily certain who did the cave paintings, but there are a number of candidate haplogroups.

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                      • #12
                        [HTMLOne model consistent with the data ][/HTML]
                        I guess I am not asking my question well. I am not really asking about who first populated France.
                        I am asking what data is being used to support a genetic migratory theory. So let me try to rephrase my question. First , haplotypes are based on the sequence of ACTG. Then the age of a particular haplotype is based on the number of mutations within it. More mutations the more ancient the haplotype. All subject to traditional error probability and scientific debate.. Is this essentially correct?

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                        • #13
                          As far as I know, the claim that humans originated in East Africa and spread to India and Australia etc is based on YDNA (and MTDNA) dna (cheek-swabs) collected by Spencer Wells of the Genographic Project (part of National Geographic). They tested men throughout the world and they claim the oldest YDNA and MTDNA in modern people is found in Africa. It's not based on autosomal dna.
                          YDNA and MTDNA developed mutations as it spread across the planet.

                          In physical appearance I think Europeans show the most genetic diversity, but science says Africa has the most genetic diversity.

                          Australian aborigines say they were first. Their legend is that they were "birthed" in Australia. I think the African-Australian YDNA may have originated on land that used to exist but was flooded and is submerged where the Arabian Sea and Indian Ocean are. Some flood survivors went east and made it to Australia, others
                          went west and made it to Africa. That is my opinion. The coastal fringe of South India has ydna traces.
                          Last edited by rainbow; 20th February 2011, 09:32 PM.

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                          • #14
                            Originally posted by Brunetmj View Post
                            [HTMLOne model consistent with the data ][/HTML]
                            I guess I am not asking my question well. I am not really asking about who first populated France.
                            I am asking what data is being used to support a genetic migratory theory. So let me try to rephrase my question. First , haplotypes are based on the sequence of ACTG. Then the age of a particular haplotype is based on the number of mutations within it. More mutations the more ancient the haplotype. All subject to traditional error probability and scientific debate.. Is this essentially correct?
                            Oldest haplotype [root]

                            ---mutation1--Haplogroup1 descendant
                            ---mutation2--Haplogroup2 descendant

                            Haplogroups in Europe are downstream of the original haplogroups. Thus, it is possible that an older haplogroup has fewer mutations.
                            Last edited by jloe; 20th February 2011, 09:37 PM.

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                            • #15
                              The haplogroup tree is the simplest, most reasonable solution of descent given a set of mutation data.

                              Mutations occur randomly from the founder, and new SNP mutations may produce new haplogroups (some of which die out).

                              See this tree:
                              http://www.isogg.org/tree/ISOGG_YDNATreeTrunk.html

                              Each code refers to a mutation, a SNP.
                              Example: y haplogroup A is defined by M91, P97 SNP mutations.

                              EDIT:
                              If you've done a y-dna test you can see the snps defining your haplogroup on your ftdna page.
                              Last edited by jloe; 20th February 2011, 09:44 PM.

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