Aryan-Dravidian
divide a myth: Study
TNN 25 September 2009, 01:16am IST
HYDERABAD: The great Indian divide along north-south lines
now stands blurred. A pathbreaking study by Harvard and
indigenous researchers on
ancestral Indian populations says there is a genetic relationship
between all Indians and more importantly, the hitherto believed
``fact'' that Aryans and Dravidians signify the ancestry
of north and south Indians might after all, be a myth.
``This paper rewrites history... there is no north-south
divide,'' Lalji Singh, former director of the Centre for
Cellular and Molecular Biology (CCMB) and a co-author of
the study, said at a press conference here on Thursday.
Senior CCMB scientist Kumarasamy Thangarajan said there
was no truth to the Aryan-Dravidian theory as they came
hundreds or thousands of years after the ancestral north
and south Indians had settled in India.
The study analysed 500,000 genetic markers across the genomes
of 132 individuals from 25 diverse groups from 13 states.
All the individuals were from six-language families and
traditionally ``upper'' and ``lower'' castes and tribal
groups. ``The genetics proves that castes grew directly
out of tribe-like organizations during the formation of
the Indian society,'' the study said. Thangarajan noted
that it was impossible to distinguish between castes and
tribes since their genetics proved they were not systematically
different.
The study was conducted by CCMB scientists in collaboration
with researchers at Harvard Medical School,
Harvard School of Public Health and the Broad Institute
of Harvard and MIT. It reveals that the present-day Indian
population is a mix of ancient north and south bearing the
genomic contributions from two distinct ancestral populations
- the Ancestral North Indian (ANI) and the Ancestral South
Indian (ASI).
``The initial settlement took place 65,000 years ago in
the Andamans and in ancient south India around the same
time, which led to population growth in this part,'' said
Thangarajan. He added, ``At a later stage, 40,000 years
ago, the ancient north Indians emerged which in turn led
to rise in numbers here. But at some point of time, the
ancient north and the ancient south mixed, giving birth
to a different set of population. And that is the population
which exists now and there is a genetic relationship between
the population within India.''
The study also helps understand why the incidence of genetic
diseases among Indians is different from the rest of the
world. Singh said that 70% of Indians were burdened with
genetic disorders and the study could help answer why certain
conditions restricted themselves to one population. For
instance, breast cancer among Parsi women, motor neuron
diseases among residents of Tirupati and Chittoor, or sickle
cell anaemia among certain tribes in central India and the
North-East can now be understood better, said researchers.
The researchers, who are now keen on exploring whether
Eurasians descended from ANI, find in their study that ANIs
are related to western Eurasians, while the ASIs do not
share any similarity with any other population across the
world. However, researchers said there was no scientific
proof of whether Indians went to Europe first or the other
way round.
Migratory route of Africans
Between 135,000 and 75,000 years ago, the East-African
droughts shrunk the water volume of the lake Malawi by at
least 95%, causing migration out of Africa. Which route
did they take? Researchers say their study of the tribes
of Andaman and Nicobar islands using complete mitochondrial
DNA sequences and its comparison those of world populations
has led to the theory of a ``southern coastal route'' of
migration from East Africa through India.
This finding is against the prevailing view of a northern
route of migration via Middle East, Europe, south-east Asia,
Australia and then to India.