COURSE NAME: M11401 Ancient Society
M. A. SEMESTER 1
TUTORIAL 1
TUTORIAL TOPIC: Critically discuss the significance of DNA studies for the understanding of history and identity, with specific reference to India.
SUBMITTED BY: Pranav Kushwaha
[DISCLAIMER: The following tutorial is being shared so students of CHS, JNU can get some idea regarding how a tutorial is to be written. This tutorial is by no means of high quality, and you might find some factual, spelling, and grammatical errors. Please refer to the BIBLIOGRAPHY section and the ENDNOTES for verifying the contents of the tutorial and for further study.
In the original file that I submitted, (i) the numbers in the square brackets were used to denote footnotes and were written in superscripts, and (ii) there was no dedicated section titled 'Endnotes', as each page contained footnotes. Endnotes are acceptable, but I'd advise you to use footnotes instead. Better yet, confirm from your professor what is required.]
This tutorial shall attempt to give a brief overview of
how DNA analysis has revolutionized our understanding of the human species in
regard to its origin. We will look upon the findings of the mitochondrial DNA,
Y chromosomal, and whole-genome analyses. A specific genetic marker, R1a, will
be discussed in detail. This will be followed by a discussion on the genetic
composition of the present-day Indian population, and what it means for the
larger question of identity as a whole. The final paragraphs of the tutorial
will go over why we need to put the breakthroughs being made in genetic science
in context with the social order of the times we are trying to study. India,
and to an extent South Asia, shall be the primary focus of this tutorial.
Over the years, a number of techniques for DNA analysis have
been developed to ascertain the origin, history, and identity of the human species.
Mitochondrial DNA (mtDNA) passes from mothers to daughters, and since it is also
prone to variation, its analysis has given us crucial insights into the
matrilineal history of populations. We have been able to track the female
ancestor of all humans, the “Mitochondrial Eve”. She is dated to have lived
around 160,000 years ago.[1] The analysis of the
chromosomal Y DNA, which passes from fathers to sons, has expanded our understanding
of the patrilineal history of populations.[2]
The sequencing of the human genome in 2001 made it possible
to read and compare the entire DNA sequence of a person. This increase in
available data – far more than mtDNA or Y chromosomal DNA analysis can ever
offer – has allowed us to understand when the parents of any given individual last
shared a common ancestor.[3] The farther up the tree lies
the common ancestor, the more genetically diverse is the person in question. The
same principle is used to differentiate between different population groups.
This technique of whole-genome analysis has provided us
with enough insight that we can distribute the people of Eurasia between three
broad groups. These are the West Eurasians (people from the Near East and
Europe), the South Asians, and the East Eurasians (people from East and
Southeast Asia). In terms of genetic makeup, South Asians stand on a middle
ground between the other two population groups.[4]
MtDNA analysis has shown that the ancient South Asian female
population bore a greater genetic similarity to its East Asian counterpart. On
the other hand, the Y chromosomal DNA analysis puts the South Asian male
population closer to its West Asian counterpart instead.[5] Hence, not only were different
populations mixing all across Asia, but West Asian men mixed with South Asian
women to a greater degree than South Asian men mixed with West Asian women over
time. Perhaps the West Asians that mixed with the South Asians were predominantly males, and few West Asian women came in contact with
South Asians as the former were outnumbered by their male counterparts. Either way, South Asian populations spent a long time in
isolation and did not mix with foreign populations, until the arrival of the
West Eurasians.[6]
As for whole-genome analysis, it has corroborated the
findings of mitochondrial and Y chromosomal DNA analyses. All three techniques
of DNA analyses uphold the African continent as the home of our species.[7]
What have these advances offered us in understanding the
history of India?
Recent research has proposed the “Ancient Ancestral South
Indian” (AASI) as an indigenous South Asian hunter-gatherer population. This
population is related to the modern-day indigenous inhabitants of the Andaman Islands.[8] The AASI mixed with the
Iranian agriculturists, an ancient people from present-day Iran, who brought
agricultural technologies from the fertile crescent.[9] This mixture is supposed to
have occurred circa 4700-3000 BCE, resulting in the birth of the “Ancestral
South Indian” (ASI) population.[10] The ASI owed twenty-five per
cent of their ancestry to these West Eurasians or Iranians.[11]
The Rakhigarhi DNA Project – undertaken by Dr Vasant
Shinde, and the lead geneticist on the project, Niraj Rai – has discovered evidence
of mixing of the AASI and the Iranian agriculturist population in the Indus
Valley Civilization (IVC) as well. Despite this West Eurasian influence, the
IVC is the “single most important source of ancestry in South Asia” in the
present day.[12] In other words, the genetic history of the
ASI and that of the IVC population are similar if not identical.
However, care must be taken before labelling any present-day
group with a high degree of IVC or ASI ancestry as the “original inhabitants”
of India. The reason is that although evidence has pointed out the existence of
the ASI about 4000 years ago, no pure or historical ASI populations exist
today. The indigenous Negrito peoples of the Andaman Islands and western
Southeast Asia are the closest we have to an “ASI proxy”, i.e., a population
group with the most resemblance to the ASI. In other words, these indigenous
people are not a perfect stand-in for the ASI as the Negrito people and the ASI last shared ancestors about 50,000 years ago.[13]
So, what do we know about the ancestry of present-day
Indians?
Present-day inhabitants of India (and of South Asia) owe
their genetic makeup to two population groups, namely, the Ancestral South
Indian (ASI) as discussed above, and the “Ancestral North Indian” (ANI). The
ANI bore a greater genetic similarity to the West Eurasians while the ASI had a
greater genetic similarity with the East Eurasians.[14]
“Genetic markers” are sections of the chromosome where even minute differences are easily detectable. These markers impart a genetic uniqueness to every individual, which helps us uncover the genetic past of not only individuals, but also of entire population groups.[15] One such genetic marker, the R1a, is believed to have originated in a population of pastoralists from the Pontic Steppe during the bronze age. It was carried over to northern Europe and northern India via migration of these communities, dated to circa 2000 BCE.[16] The R1a marker is observed only in the male Y chromosome. One subgroup of R1a mutation, R1a1a-Z93, was brought over to the Indian subcontinent by these migrating pastoralists.[17] The Iranian agriculturists and the AASI were responsible for up to seventy per cent of the ANI ancestry, until the arrival of the Steppe pastoralists contributed this distinct genetic marker to the ANI.[18]
The fact that the R1a1a-Z93 marker is foreign to the
Indian subcontinent has been reinforced by the Rakhigarhi DNA project. One of
the skeletal remains that were excavated was of a male inhabitant of the region
around 4,500 years ago. Termed as ‘I4411’[19], the individual was found devoid
of the R1a genetic marker. Rai has stated that I4411 is much more genetically
similar to South Indian tribal populations – like the Irula people of Tamil
Nadu – than to the people of west Eurasian ancestry.[20]
So, was the intrusion of the R1a genetic marker into the
Indian subcontinent accompanied by an “Aryan invasion”? There is no doubt that
the pastoralists that arrived in South Asia spoke languages classified under
the Indo-European family. This is confirmed by the Mesopotamian records of the
time that mention the presence of these Indo-Aryans in the Near East.[21] However, their migration is
not proof of an “Aryan invasion” that was theorized by the colonial rule.
We know that the IVC was an urban civilization with planned,
fortified cities. Its decline is dated to circa 1750 BCE. On the other hand,
the Vedic civilization was rural and pastoral. Moreover, Rigveda – the oldest
Veda – is dated to have been written between 1500 and 1000 BCE. These
differences in socio-cultural life, and the written records that we have access
to, strongly indicate a time-lapse between the two civilizations. These
observations place the Vedic civilization as a successor to the IVC, and not a
conqueror. Archaeological evidence points to small scale migrations in the
north-western region, and new settlements that gradually assimilated with
earlier settlements. As the IVC declined due to environmental degradation, the
people shifted to other parts of the Indian subcontinent such as the Gangetic plains,
mixing with the populations living there.[22]
Thanks to genome-wide analysis, it has become possible to
observe how the distribution of the R1a genetic marker (and the degree of
similarity to the west Eurasians) is closely related to the caste system of
India. For example, traditionally upper castes like the Brahmins are more
similar to the people from the Middle East and Europe. On the other hand,
populations belonging to the scheduled castes and tribes have little genetic
similarity to West Eurasians. Instead, they bear greater genetic similarity to the
East and Southeast Asians.[23]
As can be expected, this distribution of genes amongst
the various castes is not without its nuances. A few regional examples help us
appreciate the complexity of the situation. In descending order of genetic
similarity to the West Eurasians, we have the Brahmins of north Indian states –
like Uttar Pradesh (UP) – followed by the Brahmins from south Indian states –
like Tamil Nadu. Lower castes, like the Chamars from UP, are even less similar
to West Eurasians than south Indian brahmins. The Nadars and Reddys of South
India form a separate group that is different from the local brahmins and
scheduled castes and tribes.[24] The degree of West Eurasian
ancestry ranges from twenty per cent to eighty per cent in Indian populations.
Every population group, even the tribal populations that exist outside the
Indian caste system, has some degree of mixed ancestry.[25]
In other words, upper castes bear a greater degree of genetic
similarity to West Eurasians regardless of region. As one moves down the map
from north to south, this similarity decreases within the upper castes.
However, the degree of genetic similarity to West Eurasians is always greater
in the upper castes, differentiating them from the lower castes who always
possess a greater similarity to East Eurasians. Some communities form a separate
population group entirely. Population groups with more ANI ancestry speak
Indo-Aryan languages, while population groups with more ASI ancestry speak
Dravidian languages.[26]
The DNA evidence points to the fact that the local
population of ancient India underwent periods of considerable genetic mixing
for approximately a thousand years after the fall of the IVC. But this seems to
have stopped around two thousand years ago. Around this period, a rise in
intra-caste (or within the same caste or jati) marriages stopped gene flow
between diverse communities. This eventually made the different South Asian
populations quite homogenous internally, but quite distinct from one another.
This was accompanied by an increase in the difference between their ANI/ASI
ratio.[27]
It can be argued that DNA analysis alone does not provide
us with the full picture. The questions of our identity and history, where we come
from, who our ancestors were, can only be answered in the backdrop of the
contemporary social aspects.
The Indian caste system is one such social aspect. As
discussed earlier, the upper castes have a greater percentage of the Steppe
gene than the lower castes. But these castes were not static and immutable. The
social code – as found in the Dharmaśāstras – mandated a society rigid in structure,
where social mobility was extremely difficult, if not outright impossible.
However, the society did not always adhere to the code. There is textual
evidence of “dāsi putra Brāhman”, individuals born in the lower castes who were
assimilated into the upper caste of brahmins after proving their merit to the
orthodoxy. Their descendants would have been Brahmins of mixed ancestry.[28]
Similarly, individuals who had no royal blood in their
veins but rose to political power sought to be recognized as Kshatriyas to
solidify their right to rule. Even the Shudras – the lowest of the four varnas
– held several occupations. The Kāyasthas were of mixed background, but due to
being literate and having proficiency with Sanskrit, took on the role of bureaucrats.[29]
These examples show that just because an individual
belongs to a specific caste in the present day, does not mean that the
ancestors of that particular individual always formed part of that particular caste.
There was some level of social mobility no matter what rules the texts had laid
out.
To conclude, there is no doubt that DNA studies have
revolutionized our understanding of our history and identity. We now know for a
fact that it took several thousands of years of migration patterns, interaction
and mixing of foreign populations with local ones, and cultural and material
exchange to result in the rich and diverse state of the human society we are
now a part of. In the context of India, the question of an “original
inhabitant” population is thus rendered meaningless.
Moreover, owing to the genetic mixing that has taken
place over millennia, we need to carefully determine what sets of genetic data
gathered today are being used to understand the past. The importance of DNA
studies cannot be ignored, but we must also take into account the
socio-cultural life as was practised in the past and how it has affected the
genetic composition of the people living in the present. It is only through a combination of both that we can
truly begin to understand our nuanced history and complex identity.
ENDNOTES
[2] Razib Khan, “Genetic Origins of Indo-Aryans”, Which Of Us Are Aryans? Rethinking The Concept Of Our Origins, New Delhi: Aleph Book Company, 2019, p. 138; Reich, Who We Are, pp. 127-28.
[4] Khan, “Genetic Origins”, p. 141.
[5] Ibid., p. 140.
[6] Reich, Who We Are, pp. 127-28.
[7] Khan, “Genetic Origins”, pp. 138-39.
[8] Vagheesh M. Narasimhan et al., “The Genomic Formation of South and Central Asia”, Research Gate, March 31, 2018, p. 6. (Retrieved January 26, 2022 from https://www.researchgate.net/publication/345669286_The_Genomic_Formation_of_South_and_Central_Asia)
[9] Kai Friese, “The Complications Of Genetics”, Which Of Us Are Aryans? Rethinking The Concept Of Our Origins, New Delhi: Aleph Book Company, 2019, p. 124.
[10] Narasimhan et al., “The Genomic Formation”, p. 10.
[11] Khan, “Genetic Origins”, p. 149.
[12] Friese, “The Complications Of Genetics”, p.132; Narasimhan et al., “The Genomic Formation”, p. 4.
[13] Khan, “Genetic Origins”, pp. 142, 149.
[14] Ibid., p. 142.
[15] Keith Wailoo, Alondra Nelson, and Catherine Lee, Genetics And The Unsettled Past: The Collision of DNA, Race, and History, New Brunswick: Rutgers University Press, 2012, p. 1.
[18] Ibid., p. 150
[19] Friese, “The Complications Of Genetics”, p.121.
[20] Ibid., p. 124.
[21] Khan, “Genetic Origins”, p. 154.
[22] Romila Thapar, “Can Genetics Help Us Understand Indian Social History?”, Cold Spring Harbor Perspectives In Biology, Cold Spring Harbor Laboratory Press, June 26, 2014, pp. 5-7. (Retrieved January 24, 2022 from https://cshperspectives.cshlp.org/content/6/11/a008599.full.pdf+html); Reich, Who We Are, pp. 124-26.
[23] Khan, “Genetic Origins”, pp. 141-43; Reich, Who We Are, pp. 135-36.
[24] Khan, “Genetic Origins”, pp. 141-43.
[25] Reich, Who We Are, pp. 135-36.
[26] Reich, Who We Are, pp. 136-37.
[29] Ibid.
BIBLIOGRAPHY
Friese, Kai, “The Complications Of Genetics”, Which
Of Us Are Aryans? Rethinking The Concept Of Our Origins, New Delhi: Aleph
Book Company, 2019, pp. 119-34.
Khan, Razib, “Genetic Origins of Indo-Aryans”, Which
Of Us Are Aryans? Rethinking The Concept Of Our Origins, New Delhi: Aleph
Book Company, 2019, pp. 135-54.
Narasimhan, Vagheesh M., Nick Patterson, Priya Moorjani,
Iosif Lazaridis, Mark Lipson, Swapan Mallick, David Reich, et al., “The Genomic
Formation of South and Central Asia”, Research Gate, March 31, 2018.
(Retrieved January 26, 2022 from https://www.researchgate.net/publication/345669286_The_Genomic_Formation_of_South_and_Central_Asia)
Reich, David, Who We Are And How We Got Here:
Ancient DNA And The New Science Of The Human Past, Oxford: Oxford
University Press, 2018.
Thapar, Romila, “Can Genetics Help Us Understand
Indian Social History?”, Cold Spring Harbor Perspectives In Biology, Cold
Spring Harbor Laboratory Press, June 26, 2014. (Retrieved January 24, 2022 from
https://cshperspectives.cshlp.org/content/6/11/a008599.full.pdf+html)
Wailoo, Keith, Alondra Nelson, and Catherine Lee. Genetics And The Unsettled Past: The Collision of DNA, Race, and History, New Brunswick: Rutgers University Press, 2012.
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