Emergence of sociocultural norms restricting intermarriage (endogamy) coincides with foreign invasions of Bharat

In an excellent article in PNAS by Basu et al. (1), the authors have undertaken an impressive genomic reconstruction of the history of extant populations of Bharat. However, some limitations still remain in the sampling: the lack of genetic analysis of the patrilineal/matrilineal exogamous gotras, and the use of certain parametric values in the analysis of data presented.

Basu et al. (1) suggest that the historical period of formulation and adoption of sociocultural norms restricting intermarriage in large social strata (endogamy) coincides with the ancient regime of the Guptas. Upon using alternative, historically more appropriate, generation time parameters, another explanation that is more plausible emerges which cannot be ruled out, that endogamy originated around the time of foreign invasions of Bharat.

The arbitrary generation time parameter of 22.5 y used in the study is unsupported by evidence and is historically unsubstantiated. The near universality of marriage at a very early age in the study populations’ history posits that generation times were more likely in the range of 13–18 y, until a generation or two ago (2) (scienceblogs.com/gregladen/2011/03/01/how-long-is-a-generation/, accessed February 16, 2016).

If a generation time parameter of 22.5 y is used and one selected value of 70 generations before present alone is used, the time period in history does indeed appear to fall during the Gupta period. The Guptas reign was restricted to the northern plains, whereas different kingdoms unrelated to the Guptas ruled the vast regions of the south and southwest. Thus, the Guptas could not have enforced endogamy in the south. The authors themselves admit that the abrupt start of endogamy in the east of Bharat appears to have started during the reign of the Buddhist Pala dynasty, after the Gupta period. Thus, the onset of endogamy in the east of Bharat as well cannot be explained as a consequence of an edict from the Hindu Gupta dynasty enforcing “Vedic Brahmanism of Hinduism.”

Upon using alternative, historically more appropriate, generation time parameters (Table 1), another explanation that is more plausible emerges, that is, endogamy originated around the time of foreign invasions of Bharat (Fig. 1). The population of Bharat was estimated to be about 100–140 million 2,300 y ago and remained at about 100 million as late as 400 y ago. During this entire period of 1,900 y, Bharat remained the largest economy in the world, followed by China.

There are no recorded calamities in the history of Bharat that could have kept the population stagnant and prevented it from growing despite a continuously booming economy (2, 3). Such invasions involved complete destruction of populations and their centers of learning, scholarly work, and culture (universities, schools, and temples), such as the ancient Nalanda University and Somnath temple, to give a couple of examples.

A hugely disrupted Bharatiya society might have thus been a very fertile receptive ground for the induction of a new social order. The newly established social order could have been influenced by the invading foreign cultures, because there are known genetic markers for such endogamous grouping within Islamic societies (4, 5).

Table 1.

Estimates of time (in generations before present and in years) of contribution of each of the ancestral components to the populations considered –

Population Ancestral North Indian Ancestral Austro-Asiatic Ancestral South Indian Ancestral Tibeto-Burman
Gujarati Brahmin NA 69.3833 69.3265 *
 13 902 901
 15 1,041 1,040
 18 1,249 1,248
West Bengal Brahmin NA 69.5409 68.3778 63.3518
 13 904 889 824
 15 1,043 1,026 950
 18 1,252 1,231 1,140
Maratha NA 48.7989 48.92 *
 13 634 636
 15 732 734
 18 878 881
Iyer NA 69.1751 71.699 *
 13 899 932
 15 1,038 1,075
 18 1,245 1,291
Pallan NA 74.3893 76.1979 *
 13 967 991
 15 1,116 1,143
 18 1,339 1,372
Kadar 47.5509 60.7911 NA *
 13 618 790
 15 713 912
 18 856 1,094
Irula 39.4951 49.8475 NA *
 13 513 648
 15 592 748
 18 711 897
Gond 77.6637 91.9575 70.509 58.1287
 13 1,010 1,195 917 756
 15 1,165 1,379 1,058 872
 18 1,398 1,655 1,269 1,046
Ho 54.0405 NA 67.8753 52.9333
 13 703 882 688
 15 811 1,018 794
 18 973 1,222 953
Santal 54.8661 NA 71.5929 61.5647
 13 713 931 800
 15 823 1,074 923
 18 988 1,289 1,108
Korwa 46.5407 NA 55.7532 46.6478
 13 605 725 606
 15 698 836 700
 18 838 1,004 840
Manipuri Brahmin 69.7002 67.6769 70.4008 NA
 13 906 880 915
 15 1,046 1,015 1,056
 18 1,255 1,218 1,267
Tharu 62.7826 65.2317 72.9749 NA
 13 816 848 949
 15 942 978 1,095
 18 1,130 1,174 1,314
Tripuri 65.1124 69.6447 70.5565 NA
 13 846 905 917
 15 977 1,045 1,058
 18 1,172 1,254 1,270
  • The numbers 13, 15, and 18 are historically more appropriate generation times; the units of corresponding values in cells below generations before present are years. NA, not applicable.

  • * The contribution of the ancestral component is too low for reliable estimation of time depth.

Figure 1.

Map of Islamic dynasties of Bharat with their extent over relevant time periods. Image courtesy of Javier Fernandez-Vina (Florida International University, Miami, FL)

Footnotes

  • Author: Murali KV (A medic and a graduate of the University of Cambridge, England,  involved in inter-disciplinary research for the inculcation of a scientific rigour in the outdated  fields of humanities: putting “science” into social sciences)

References

  1.   Basu A, Sarkar-Roy N, Majumder PP (2016) Genomic reconstruction of the history of extant populations of India reveals five distinct ancestral components and a complex structure. Proc Natl Acad Sci USA 113(6):1594–1599 Abstract/FREE Full Text
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