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.

• 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.

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)

• This paper first appeared at http://m.pnas.org/content/113/16/E2215.full and is being reproduced with the consent of the author.

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
2. ↵  Romaniuk A (2013) Glimpses of Indian historical demography. Can Stud Popul 40(3–4):248–251. Google Scholar
3. ↵ Sussman GD (2011) Was the black death in India and China? Bull Hist Med 85(3):319–355
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4. ↵ Aarzoo SS, Afzal M (2005) Gene diversity in some Muslim populations of North India. Hum Biol 77(3):343–353. CrossRef    Medline    Google Scholar
5. ↵ Ambedkar BR (1941) Thoughts on Pakistan (Thacker and Company Limited, Bombay), pp 221–224.    Google Scholar

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