Some further thoughts, not strongly apropos of anything...

It's an interesting chart, but I think it's incomplete because it shows only genes radiating outward from Africa--its agenda is to illustrate the "Out of Africa" picture--and leaves out the more complicated circulatory patterns. The intervals between radial waves might make more sense if you could see the period required to walk out to some terminus like Australia and then return. The combination of speed of travel with the mutation rate would set up distinct natural rhythms and harmonies in the flow.

The chart is restricted to the recent homo sapiens line, and leaves out the earlier circulation of hominids through Africa and Eurasia. These earlier waves are important to the picture because their genes also split and recombined in the "crockpot" of genes cooking in Africa, albeit much more slowly than our later and faster-moving ancestors.

There's another map I don't have a link to, but it's easy enough to visualize: The spread of civilization out of the Fertile Crescent. That chart is interestingly parallel to the spread of genes, because civilization followed the same migratory paths as the genes, albeit with headwaters shifted to the northeast to a more promising environment.

That map is interesting too, because to my eye it illuminates otherwise inexplicable cultural affinities. The English found themselves liking the Indians when they finally sailed around to visit and conquer, and India had a special place in the British Empire. As creepy as it is to the modern ear, there's no doubt that the English intended "White Oriental Gentleman" to be a compliment in the form of an implication of kinship; the words show the English struggling to resolve the contradiction between appearance and their sense of familiarity.

My theory is that it's something like birth order: English civilization and Indian civilization are a similar distance out along the migratory path of civilization from the Fertile Crescent. Though the two cultures are superficially wildly different, in some sense they had similar "life experiences". When the European branch of the flow of civilization circled around to meet the Indian branch, they combined to form a strong hybrid that heavily influenced the future development of both of them.

My point in mentioning all this is that tree-based depictions of human history are too simple to capture the intricate patterns. It's all about whirlpools and eddies and rivers, eternal cycles of goodbyes and reunions.

I also have a cautionary point: Radial depictions imply a one-way flow, and this leaves people inclined to prejudice and chauvinism free to interpret the chart to mean that genes out at the edges of the flow are more advanced than those that "remained" in Africa; or that cultures at the end of the flow are more advanced than those in the core Middle East. The reality is nowhere near that simplistic, because of the constant feedback and refreshing of genes and cultures in the circulatory picture.