Ikram Saeed asks:
I would agree that China is less diverse than India, but it is still extremely diverse. And south China is the most distinct region of all, with several unintelligible “chinese” languages.
Are Chinese emigrants disproportionately from the south? US and Canadian Chinese populations arise largely from southern China. The only country I know of which has Chinese residents originating from many parts of China is Taiwan.
But this is blog is best when it is quantitive. What is the genetic similarity between northern, southern, and inland residents of China? Compare with India?
On north Chinese vs. south Chinese, Ikram is of course correct that the “dialects” of the south are languages by another name (while the “languages” of Scandanavia are dialects by another name). But, for the lay person, Ikram forgets to mention that all Chinese (Han, Zhongguo-Ren, Huaren, whatever) share a common written language, ergo, their ruling elite share a literary culture & canon. Perhaps an analogy might be made with medieval Latin in Christendom, the difference being that in this case 75% of Christendom shares the same colloquial language to boot.
As for the genetics, this is a complex question (speaking of complex, some bloggers & readers might be interested in this overview of Hakka genetics). Joanna Mountain, working with Cavalli-Sforza, has done work that indicates that south Chinese share an earlier common ancestry with southeast Asians than north Chinese. Historically this is plausible, the Vietnamese ancestral homeland is located just south of the Pearl River Delta while the Thai people still retain a prescence in southern China as the “Dai.” Just as Indo-Aryan languages like Marathi have been characterized as “Indo-European with a Dravidian accent,” so one could depict the south Chinese dialects in a similar manner. Of course, I have recently come to be skeptical of connecting shared ancestry marked by neutral genes to the genetic heritage of phenotypically significant traits (in other words, south and north Chinese might share different mother & father lines, but their genes that influence phenotype might have been selected so that a common phenotype has developed-this is obviously important from the perspective of human biodiversity).
The idea that the migrants that formed the Chinese Diaspora were self-selected is persuasive on the surface (to me at least). The Taiwanese, Singaporeans & Hong Kong Chinese share about the same per capita income. But, there is a difference: while Singapore & Hong Kong have incomes of 24 K and 25 K, Taiwan is at 17 K (not an economist, so I don’t know if “purchasing power parity” takes into account that the two cities almost certainly have sky high cost of living). Could this be because the inhabitants of the two cities are more self-selected than the “Taiwanese” ? I would like to know the per capita incomes of the Chinese of Malaysia, Thailand and Indonesia (though the last is a bit confusing, as the Chinese are bifurcated into the “Totok” and “Perakanan” communites, the latter being somewhat like the Baba Chinese of Malaya).
Update: From the message board:
Here’s a paper that suggests that there is no difference between Northern and Southern Chinese
Posted by js at February 27, 2003 03:40 PM
 Hong Kong is a mostly Cantonese city with a prominent clique of Shanghai capitalists. Singapore is more mixed, but I believe (someone can correct me) that most are descendents of migrants from Fukien. The “Taiwanese” are ~90% Fujianese in origin, migrating over a long period of time from Manchu conquest down to the period of Japanese rule, the remaining 10% are mainlanders, predominantly from north China. The indigenous Formosan Taiwanese are irrelevant to this discussion, and numerically negligible (I’m not a linguistic specialist, apologize for the misappellation Malayo-Polynesian).