I?m sorry. I couldn?t resist it. I?m still on holiday so have time on my hands. Hope this isn't too long. So drawing on my knowledge of evolution and genetics here?s my interpretation of where Adam and Eve came from and the routes their descendants? took as they spread around the world. I look forward to any criticism anyone is prepared to offer. The account is derived mostly from the information on diagrams and maps of the human Y-chromosome (male) and mtDNA (female) lines at these two sites:
http://www.scs.uiuc.edu/~mcdonald/WorldHaplogroupsMaps.pdf
http://en.wikipedia.org/wiki/HaplogroupUnlike most researchers I will not automatically assume an ancient Moses led a group of modern humans out of Africa. I would remind you that expanding lines displace, or at least reduce, previous Y-chromosome and mtDNA lines in any region. Migrations are usually long, drawn-out processes though. Genes from earlier populations frequently survive. Modern Y-chromosome and mtDNA distribution is usually accepted as being a result of cultural and technological expansion. Perhaps we should assume the same was true for ancient movements, even as far back as Homo habilis times.
Of course we cannot automatically assume any ancient, or even modern, migrations always include both men and women. It isn?t only married men who migrate to new regions. For example in several South American groups virtually all the Y-chromosomes are European while the mtDNA is entirely from local indigenous people. Any man who travels a lot can spread his genes, including his Y-chromosome, quite widely. For many reasons women?s genes spread more slowly. The two lines can be remarkably independent.
The first thing to notice about the maps is that geographical extremities generally retain older lines. On the other hand the Iranian plateau and Central Asia have always been a main highway. A whole series of migrations have zipped through there and left descendants. Each new migration has lowered the proportion of pre-existing lines. When we turn to the family trees the first thing we notice is that although Adam and Eve both lived in Africa there is a gap of at least 60,000 years between mtEve and Y-chromosome Adam. In fact by the time Y-chromosome Adam evolved the mtDNA line seems to have already split into an M and N version. This raises the question of what people had mtEve?s line been breeding with to sustain the mtDNA line over those 60,000 years?
The splits in the mtDNA line within Africa seem to simply indicate a slow northward movement from southern Africa beginning about 150,000 years ago. In spite of any propaganda M and N didn?t come out of Africa themselves. Their ancestors came out sometime after the mutation that gave rise to L3 in Africa, perhaps as long ago as 85,000 years. Modern humans had certainly made it into the Middle East by 90,000 years ago. Neanderthals replaced them there about 70,000 years ago but it?s likely the mtDNA remained. The lines M and N were selected for outside Africa, perhaps divided by habitat when they came up against the first obstacle to their expansion: the Zagros and Taurus Mountains. At a guess I?d say N developed in the south-facing hilly regions while M went round the end onto the open Iranian and central Asian plains.
After what seems to have been a period of selection M?s line and her descendants rapidly expand east through central Asia to the far shore and then south along it. Y-chromosome Adam?s descendants may have caught up with them by this time. But for quite a while mtEve?s descendants may have had children with men already there. Back at the western end of the distribution M?s line eventually gets into India from the Northwest, almost certainly with Adam?s Y-chromosome line. After M?s initial expansion around the world a series of mutations give rise to regional varieties. Eventually one of these mtDNA lines (Q), along with a small amount of M?s line, makes it to New Guinea, probably about 30,000 years ago. Just a small proportion of M gains a toehold in Australia, but no Q. Others of M?s descendants remain in Central Asia and eventually move to America (C and D).
A few of N?s line and her descendants eventually move onto the plains as well and follow M. They move through territory already occupied by M and her descendants, into Iran and the Middle East, and a few of N?s descendants even move back to North and East Africa. But in Asia N eventually moves past M?s descendants and arrives in Australia at least by 50,000 years ago. N?s descendants A, B and I eventually reach America.
From this time on it gets complicated. There was a huge expansion of R?s mtDNA line at some time. R evolved from N, possibly in Wallacea, and her descendants are spread from North Africa, across Central and Eastern Eurasia, into America and right down to Australia, New Guinea and Polynesia. R?s descendants mixed with earlier lines including M and N lines and their descendants. But by this time mtDNA lines had been reduced to just those of mtEve. At the western end of the R mtDNA expansion H, T, J and U along with a little N move into Europe.
Now a look at the Y-chromosome line. The first split in the Y-chromosome Adam line seems to be when a group moves into the Central African forest, perhaps a little more than 60,000 years ago. This Y-chromosome line, B, is especially common in modern day Pygmies. The defining moment for the Y-chromosome Adam line outside Africa appears to be when it reaches India. This may be associated with the movement of mtEve?s M line into that continent. All modern non-African Y-chromosomes descend from just two, or possibly three, lines. C probably originated on the Iranian plateau, but it moved into northern India and also to central and eastern Asia. This C Y-chromosome line eventually crossed central Asia to reach Australia, probably with mtEve?s line N.
The expansion of D and E must be more recent than the YAP Y-chromosome mutation that defines them, about 50,000 years ago. E expanded around Africa in force and moved into the Middle East. There is possibility evidence interpreted as a migration out of Africa 40,000 years ago is actually evidence for a migration into Africa.
F seems to have originated in India. Some of his descendants also move north and follow C?s expansion but they don?t move as far. Some of these people (Y-chromosomes I and J) may give rise to the Cro-Magnon of Europe. Others of F?s descendants (K) go in the other direction and follow the coast east, presumably breeding with women they meet on the way. For several reasons these women are unlikely to belong to the mtEve line but M?s mtDNA line may have gone with them. It?s more likely that the mtEve line M had already moved south down the east coast long before. In Southeast Asia the lines definitely meet. The two lines, along with M?s descendant Q, move to New Guinea about 30,000 years ago. Y-chromosome K also moves into already occupied Australia. There seems to have then been an expansion of Y-chromosome K?s descendants west and north back from around New Guinea, probably associated with improved boating technology developed in Wallacea. This expansion is particularly interesting. One of its descendants (Y-chromosome R) reaches Europe, possibly with the descendants of R mtDNA.