Genetic Evolution in South Indian Caste Populations

人类学家长期以来一直对生物学和文化之间的关系感兴趣。印度种姓制度在印度人口中确立了择偶习惯，这是社会进程对人类生物学影响的一个很好的例子。许多研究者研究了种姓制度对遗传变异的影响。然而，由于几个原因，这项工作的概括仍然不令人信服。首先，许多分析的多态性是DNA变异的间接测量，仅从少数位点取样，并且不是选择性中性的。其次，许多研究没有估计显著性水平或置信区间，使研究结果令人怀疑。最后，没有系统的比较与大陆人口（即非洲人，亚洲人和欧洲人）使用一个大的，统一的DNA多态性集。迄今为止，还没有人利用分子生物学的最新进展来解决印度人类进化中长期存在的重要问题。拟议的研究将通过以下方式批判性地研究南印度种姓群体的遗传进化：(1)制定和检验种姓细分对遗传变异影响的假设；(2)利用多种线粒体和核DNA多态性；(3)与大陆人口进行直接比较。该研究将分析线粒体DNA、y染色体DNA和常染色体DNA多态性的不同突变率，这些样本来自跨越种姓制度的4个种姓和2个部落人群。将与我们现有的种姓和大陆人口数据进行比较。

Anthropologists have long been interested in the relationship between biology and culture. The Hindu caste system, which established preferred mating practices among the populations of India, is a good example of the impact of social processes on human biology. Numerous investigators have studied the effect of the caste system on genetic variation. Yet the generalizations from this body of work remain unconvincing for several reasons. First, many of the polymorphisms assayed are indirect measurements of DNA variation, are sampled from only a few loci, and are not selectively neutral. Second, many studies do not estimate significance levels or confidence intervals, leaving the findings suspect. Finally, no systematic comparisons have been made with continental populations (i.e., Africans, Asians, and Europeans) using a large, uniform set of DNA polymorphisms. To date, no one has taken advantage of the recent advances in molecular biology to address unresolved questions of long-standing importance to human evolution in India. The proposed research will critically investigate the genetic evolution of South Indian caste populations by (1) formulating and testing hypotheses of the effect of caste subdivision on genetic variation; (2) using a variety of mitochondrial and nuclear DNA polymorphisms; and (3) making direct comparisons to continental populations. The study will analyze mitochondrial DNA, Y-chromosomal DNA, and autosomal DNA polymorphisms with differing rates of mutation from a sample representing individuals in 4 castes spanning the caste hierarchy and 2 tribal populations. Comparisons will be made to our existing data from caste and continental populations.