Razib Khan One-stop-shopping for all of my content

May 4, 2017

The great Han Empire in Africa

Filed under: Africa,Chinese,Chinese in Africa,Culture,History — Razib Khan @ 10:23 pm

Howard French’s China’s Second Continent: How a Million Migrants Are Building a New Empire in Africa is a bit cliche. Rather than a scholarly book it’s more an observational travelogue, and it suffers somewhat from the fact that it is focused on Chinese who live in Africa, but are never of it. Chinese are Chinese, and those who migrate to Africa have more commonalities than most. So French’s attempts to spin out distinct experiences was a bit stretched. Basically, the same thing is happening over and over across the African continent.

When I say this that it is cliche, I’m alluding to the fact that for many Chinese presence in Africa is rather well known. But the reality is not everyone knows about it. So I was happy to see The New York Times put this issue front and center, Is China the World’s New Colonial Power?

There are twists which are important to remember. First, China’s working age population has been declining since 2012. This is going to put a crimp in any “imperial” ambitions. Second, this Chinese “empire” is not going to be an explicitly political one, but rather one of influence, control, and tough soft power.

That being said, we should’t underestimate the will and need of the Chinese to have their “time in the sun.” Fifteen years ago Ross Terrill wrote The New Chinese Empire. In it be observed that for much of Chinese history there has long been a division between a moralistic/ideological camp and a more nationalist realpolitik element. He traces this division back to antiquity, with Confucianism and Legalism as the prototypes (I’m not sure I believe this). But Terrill observed that Deng Xiaoping and the leaders who he cultivated and promoted to succeed him were generally much more nakedly nationalistic than Mao ever was.

Just something to keep in mind as we look to the future….

November 25, 2009

GWAS, population structure and the Han Chinese

Filed under: Chinese,Genetics,Han,Population genetics — Razib @ 1:47 pm

Two new articles in AJHG, Genomic Dissection of Population Substructure of Han Chinese and Its Implication in Association Studies:

To date, most genome-wide association studies (GWAS) and studies of fine-scale population structure have been conducted primarily on Europeans. Han Chinese, the largest ethnic group in the world, composing 20% of the entire global human population, is largely underrepresented in such studies. A well-recognized challenge is the fact that population structure can cause spurious associations in GWAS. In this study, we examined population substructures in a diverse set of over 1700 Han Chinese samples collected from 26 regions across China, each genotyped at ∼160K single-nucleotide polymorphisms (SNPs). Our results showed that the Han Chinese population is intricately substructured, with the main observed clusters corresponding roughly to northern Han, central Han, and southern Han. However, simulated case-control studies showed that genetic differentiation among these clusters, although very small (FST = 0.0002 ∼0.0009), is sufficient to lead to an inflated rate of false-positive results even when the sample size is moderate. The top two SNPs with the greatest frequency differences between the northern Han and southern Han clusters (FST > 0.06) were found in the FADS2 gene, which associates with the fatty acid composition in phospholipids, and in the HLA complex P5 gene (HCP5), which associates with HIV infection, psoriasis, and psoriatic arthritis. Ingenuity Pathway Analysis (IPA) showed that most differentiated genes among clusters are involved in cardiac arteriopathy (p < 10−101). These signals indicating significant differences among Han Chinese subpopulations should be carefully explained in case they are also detected in association studies, especially when sample sources are diverse.

And, Genetic Structure of the Han Chinese Population Revealed by Genome-wide SNP Variation:

Population stratification is a potential problem for genome-wide association studies (GWAS), confounding results and causing spurious associations. Hence, understanding how allele frequencies vary across geographic regions or among subpopulations is an important prelude to analyzing GWAS data. Using over 350,000 genome-wide autosomal SNPs in over 6000 Han Chinese samples from ten provinces of China, our study revealed a one-dimensional “north-south” population structure and a close correlation between geography and the genetic structure of the Han Chinese. The north-south population structure is consistent with the historical migration pattern of the Han Chinese population. Metropolitan cities in China were, however, more diffused “outliers,” probably because of the impact of modern migration of peoples. At a very local scale within the Guangdong province, we observed evidence of population structure among dialect groups, probably on account of endogamy within these dialects. Via simulation, we show that empirical levels of population structure observed across modern China can cause spurious associations in GWAS if not properly handled. In the Han Chinese, geographic matching is a good proxy for genetic matching, particularly in validation and candidate-gene studies in which population stratification cannot be directly accessed and accounted for because of the lack of genome-wide data, with the exception of the metropolitan cities, where geographical location is no longer a good indicator of ancestral origin. Our findings are important for designing GWAS in the Chinese population, an activity that is expected to intensify greatly in the near future.

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