India is a classic example of genetic potpourri. Though the Ancestral South Indians (ASIs) found in the four southern States are not related to any group outside India, populations in the north Indian States known as Ancestral North Indians (ANIs) exhibit a close genetic affinity to middle easterners, central Asians, and west Eurasians. The Nyshi and Ao Naga populations from north-east India show genetic affinity to the Chinese. The small Siddi population found in Karnataka, Gujarat and some parts of Andhra Pradesh shows an African affinity. Though the genetically admixtured tribal Siddi group exhibiting Indian and typical African features like dark skin, curly hair, and a broad nose has been around for a few hundred years, no comprehensive study was done to establish its African genetic kinship. This lacuna has been finally addressed by a study published in The American Journal of Human Genetics (“Indian Siddis: African descendants with Indian admixture,” by Anish M. Shah et al.). The study is robust as the authors have analysed genetic markers from non-sex chromosomes (autosomes), and paternally derived Y-chromosomes and maternally derived mitochondrial DNA (mtDNA). An analysis of both Y-chromosomes and mtDNA, and autosomes in Siddis and the adjoining Indian tribal populations has helped in tracing the direction of gene flow between the African descendent and Indians. Sixty Siddis and 90 people from the adjoining tribal populations in Junagarh district of Gujarat, and 94 Siddis and 178 people from adjoining tribal populations in Uttara Kannada district of Karnataka were studied.
There is overwhelming evidence of gene flow from Indians to the Siddi population. Nearly 65 per cent of maternally derived mtDNA found in the Siddis represents Indian ancestry (with minor contribution from Europeans). Even in the case of the Y-chromosome, which is transmitted by fathers only to sons, nearly 30 per cent has come from Indians. The evidence is further strengthened by the non-sex chromosomes. Nearly 30 per cent of Indian gene signature is seen in the case of the autosomes, which are equally contributed by mother and father to the offspring. Incidentally, no genetic signature of African ancestry is found in the Indian populations adjoining the Siddis. All these together establish an unequivocal unidirectional gene flow from the local Indian groups to the Siddis. The study has for the first time traced the Siddi's African ancestry to the Bantu-speaking population in the sub-Saharan region, and established that the gene admixture happened only over the past eight generations — about 200 years ago.
Keywords: mitochondrial DNA, Human Genetics
My interest in the siddis grew when i watched a moving kannada film on them by noted film-maker Girish Kasaravalli which won the National Award last year. A very interesting study indeed!
The definitive studies are by Stephen Oppenheimer of Oxford and L. Cavalli-Sforza of stanford. They unequivocally conclude that there was little or no gene inflow into India in the Holocene, i.e., since the ending of the last Ice Age more than 10,000 years ago. It is not scientific to mix up language and genes. Aryans and Indo-european are cultural constructs that have never existed as humans. The article cited appears to be an attempt to revive the discredited Aryan-Dravidian divide by claiming genetic support.
The publication in question, The American Journal of Genetics has a checkered record. It carried the now discredited (and retracted) article by Bamshad et al claiming a genetic link between the 'invading' Europens and upper castes. The present article seems to fall in a similar category and its conclusions are not supported by serious researchers.
the 'Out-of-Africa' hypothesis suggests that the anatomically modern humans originated in Africa about 160,000 - 150,000 years ago. Thus genetic science speaks against any racial diferentiation amongst humans. Furthermore, the Indian mtDNA gene pool is very unique, as coalescence period of India-specific haplogroups is more than 40000 years.Their virtual absence elsewhere in the world suggest a limited gene outflow out of India. A study made by Sengupta and others in 2006 indicates that influence of Central Asia on the pre-existing gene pool was minor. It also says that pre-Holosene and Holosene era and not Indo Europeans have shaped South Asian Y-chromosme landscape. A study made by S. Roychoudhary and others also suggests western haplogroups found in India may have been present in India prior to entry of 'Aryan' speakers. Hence, re-appraisal of earlier theories in regard to 'Aryans' as well as Indus valley people is felt necessary.
Dear Editor,
ASI has nothing to do with the 4 states of south India. The 'principal component' that is crystallised as ASI is most clear in the indigenous Andaman islander population. the 4 'South Indian' states are populated by people with a mixture of ASI and ANI genes as are 'North Indians' although the ANI proportion increases in a northwesterly direction beginning from 0 in the andaman islands to very high in the north-west frontier.
Equating ASI with the '4 southern states' only serves to substantiate the dravidian-indo aryan linguistic difference with a genetic component. If such a genetic difference exists, then it is not explained by looking through the ANI-ASI prism. I am not a geneticist. But I have read the paper in Nature that first introduced the ANI-ASI framework. I invite you to read it too.
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