By Syed Akbar
"Ghar Jamai". The very word stirs up the masculine conscience of every man.
A man generally do not like to be a "Ghar Jamai" (man moving over to wife's
house after marriage) because he feels that it leads to subjugation of his
"manly" respect and self-esteem.
Culturally and traditionally the concept of "Ghar Jamai" may have hurt the
sentiments of the male species of Homo Sapiens, but geneticists say that this
practice has little to do with the variation in the gene make-up of a
population, at least in India.
World-wide the "Ghar Jamai" concept might have led to vast variations in the
gene make-up of local populations because of the flow of male chromosomes
from one locality and group to another. But as far as Indian populations are
concerned, the traditional view of geneticists on this concept does not hold
water.
The reason, anthropologists and geneticists, argue is that Indian populations
are quite different from those living elsewhere in the world. This is because
marriages in India, by and large, are based on caste, religion, language and
regional considerations.
India, with its vast populations divided on caste, religion, linguistic and
regional lines, is unique as far as genetic variation is concerned. No other
nation in the world shows such genetic patterns as exhibited by the Indian
people. The uniqueness of Indian populations is that they are mostly
endogamous i.e. marriages are guided by cultural and traditional practices
and are held within the given community, caste or group. The view held by
geneticists world over thus far is that the gene flow chart in both patrilocality
(man moving over to wife's place after marriage) and matrilocality (woman
moving over to husband's place after marriage) are uniform the world over.
But Indian scientists dispute this saying that it does not apply to Indians.
"The patterns of genetic variation in humans are not universal, but depend on
local cultural practices," says Prof B Mohan Reddy of Indian Statistical
Institute, Hyderabad.
In most human societies, women traditionally move to their husband's home
after marriage, an these societies are thus "patrilocal", but in a few
"matrilocal" societies, men move to their wife's home. These social customs
are expected to influence the patterns of genetic variation.
They should lead to a localisation of male-specific Y-chromosomal variants
and wide dispersal of female-specific mitrochondrial DNA variants in
patrilocal societies and vice versa in matrilocal societies.
These predicted patterns have indeed been observed in previous studies of
populations from Thailand.
Indian societies, however, are endogamous, so marriage should always take
place within a population, and these different patterns of genetic variation
should not build up.
The study carried out jointly by the Biological Anthropology Unit of ISI, the
Centre for Cellular and Molecular Biology, Department of Anthropology,
North Eastern Hill University, Shillong, GSF Hematologikum, Munchen,
Germany, LV Prasad Eye Institute and Kallam Anji Reddy Molecular
Genetics Laboratory, has analysed 10 patrilocal and five matrilocal Indian
populations, and found that there is indeed little difference between the
patrilocal and matrilocal societies. The patterns of genetic variation in
humans are not universal, but depend on local cultural practices.
"The spatial instability of the impact of different cultural processes on the
genetic variability has resulted in the lack of universality of the hypothesised
pattern of greater Y-chromosome variation when compared to that of
mitochondrial DNA among the patrilocal populations," the study observed.
The males posses Y-based sex genes while the females contribute
mitochondrial genes. The mitochondrial genes are given by mothers to
daughters while Y-chromosomes are passed on from fathers to sons.
The variability (or genetic distances) within a population (i.e. same caste,
tribe, religion, region etc) in case of patrilocal concept is high for
mitrocondrial genes. The variability will be lower between two or many
populations in this case, because when woman moves the mitochondria also
moves which reduces the genetic distances between various groups.
In case of matrilocal societies (Ghar Jamai) the Y-chromosome moves with
the husband and this reduces variability between populations for "Y" and
increase variability within the population.
"This was the evidence found in Thailand and other places. But this cannot
be universal for all societies. In the Indian context, populations are highly
endogamous. So the variability generally found in other countries is not
observed in the Indian context," argues Vikrant Kumar, one of the
researchers.
For populations bound by rigid endogamy rules with their boundaries
absolutely impermeable, neither patrilocality nor matrilocality can make any
difference to their genetic variability, be it Y-chromosome or mitochondrial
DNA. This is so, because the gene movement is restricted to within a
population, Prof Mohan Reddy pointed out.
The populations included in this study are Maram, Khynriam, Pnar, Bhoi and
WarKhasi, the five matrilocal Khasi tribes of Meghalaya, and Asur, Bhumij,
Kharia, Munda and Santhal, the five patrilocal Mundari tribes of Eastern
India. To guage the consistency in the genetic patterns within broad regional
or cultural context, the same set og genetic data were generated on the five
Dravidian language-speaking patrilocal caste populations of Andhra Pradesh
i.e. Akutota, Kapu, Panta, Pokanati, and Vanne and compared with the north-
Indian matrilocal tribes.
Blood samples from 636 individuals belonging to 15 populations were
obtained for the study.
Sunday, 3 June 2012
Genetics all in a family: Marvellous are the functions of the genes
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment