This genetic map of East Asia appears to be formed by running a Principal Component Analysis (PCA), taking the two largest components, using those as horizontal and vertical axes, and then rotating them. PCA is one of many techniques in a href=”http://www.statmethods.net/advstats/factor.html”>multivariate statistics that allow explortation of ‘unknown unknowns’ — what variables did you not measures, but which secretly are influencing the variables you did measure?
The genetic map of Asia looks even more like a ‘map than the Genetic Map of Europe that was featured at Catholicgauze, gnxp, and here earlier. Japanese and Koreans (two historically closed-off populations) look like ‘islands.’ Likewise, ‘Chinese Americans’ are placed on this map somewhere around Taiwan, which makes sense given that the old Chinese population in America comes largely from the Cantonese region of China.
Just as genetics is helping make geography mroe quantitative and more meaningful, quantatitive analysis is also transforming history from a collection of stories to a real social science. Razib’s post on North African and Jewish influences in the Spanish population is, hopefully, an example of history is becoming.