英國《自然》雜志24日刊登文章說,，迄今規(guī)模最大的關(guān)于印度人的基因測序證實,，今天的印度人起源于一南一北兩個不同的祖先群體,。這項基因研究還證實，印度的種姓制度已有幾千年歷史,。
印度擁有全球約六分之一的人口,，但對其基因特征的研究卻一直較少。美國和印度研究人員在這次基因研究中,，分析了來自不同地點,、不同種姓、不同部族的25個人口群落,，涵蓋了全印度的人口基因特征,。
結(jié)果顯示，印度人起源于一南一北兩個不同的祖先群體,，其中北方祖先群體的基因與今天中東、中亞和歐洲人的基因相近,，而南方祖先群體的基因比較獨(dú)特,，與南亞大陸以外其他任何人群的基因都不相近。今天大部分印度人都含有來自這兩個祖先群體的基因,。
研究人員說,，基因分析還顯示印度有一些不同人群在同一個村莊里生活了幾千年，卻從來沒有交換過基因,，這證實只允許內(nèi)部通婚的印度種姓制度已有幾千年的歷史,。研究人員提醒說，需要注意這種由于嚴(yán)格的內(nèi)部通婚而引起的遺傳疾病風(fēng)險,。
此前,，歷史學(xué)家和考古學(xué)家已對印度人的起源得出過類似的基本結(jié)論，但《自然》為這篇封面文章配發(fā)的評論說,，這一研究對印度人祖先基因圖譜的精確分析,、對其祖先基因的混雜和變化趨勢等結(jié)論都是全新的重要進(jìn)展，對印度的人類學(xué),、醫(yī)學(xué)甚至社會學(xué)等研究都有深遠(yuǎn)意義,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 461, 489-494 (24 September 2009) | doi:10.1038/nature08365
Reconstructing Indian population history
David Reich1,2,5, Kumarasamy Thangaraj3,5, Nick Patterson2,5, Alkes L. Price2,4,5 & Lalji Singh3
1 Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
2 Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, USA
3 Centre for Cellular and Molecular Biology, Hyderabad 500 007, India
4 Departments of Epidemiology and Biostatistics, Harvard School of Public Health, Boston, Massachusetts 02115, USA
5 These authors contributed equally to this work.
6 Correspondence to: David Reich1,2,5Lalji Singh3 Correspondence and requests for materials should be addressed to D.R. or L.S.
India has been underrepresented in genome-wide surveys of human variation. We analyse 25 diverse groups in India to provide strong evidence for two ancient populations, genetically divergent, that are ancestral to most Indians today. One, the 'Ancestral North Indians' (ANI), is genetically close to Middle Easterners, Central Asians, and Europeans, whereas the other, the 'Ancestral South Indians' (ASI), is as distinct from ANI and East Asians as they are from each other. By introducing methods that can estimate ancestry without accurate ancestral populations, we show that ANI ancestry ranges from 39–71% in most Indian groups, and is higher in traditionally upper caste and Indo-European speakers. Groups with only ASI ancestry may no longer exist in mainland India. However, the indigenous Andaman Islanders are unique in being ASI-related groups without ANI ancestry. Allele frequency differences between groups in India are larger than in Europe, reflecting strong founder effects whose signatures have been maintained for thousands of years owing to endogamy. We therefore predict that there will be an excess of recessive diseases in India, which should be possible to screen and map genetically.
