(Press-News.org) Scientists from Harvard Medical School and the CSIR-Centre for Cellular and Molecular Biology in Hyderabad, India, provide evidence that modern-day India is the result of recent population mixture among divergent demographic groups.
The findings, published August 8 in the American Journal of Human Genetics, describe how India transformed from a country where mixture between different populations was rampant to one where endogamy—that is, marrying within the local community and a key attribute of the caste system—became the norm.
"Only a few thousand years ago, the Indian population structure was vastly different from today," said co–senior author David Reich, professor of genetics at Harvard Medical School. "The caste system has been around for a long time, but not forever."
In 2009, Reich and colleagues published a paper based on an analysis of 25 different Indian population groups. The paper described how all populations in India show evidence of a genetic mixture of two ancestral groups: Ancestral North Indians (ANI), who are related to Central Asians, Middle Easterners, Caucasians, and Europeans; and Ancestral South Indians (ASI), who are primarily from the subcontinent.
However, the researchers wanted to glean clearer data as to when in history such admixture occurred. For this, the international research team broadened their study pool from 25 to 73 Indian groups.
The researchers took advantage of the fact that the genomes of Indian people are a mosaic of chromosomal segments of ANI and ASI descent. Originally when the ANI and ASI populations mixed, these segments would have been extremely long, extending the entire lengths of chromosomes. However, after mixture these segments would have broken up at one or two places per chromosome, per generation, recombining the maternal and paternal genetic material that occurs during the production of egg and sperm.
By measuring the lengths of the segments of ANI and ASI ancestry in Indian genomes, the authors were thus able to obtain precise estimates of the age of population mixture, which they infer varied about 1,900 to 4,200 years, depending on the population analyzed.
While the findings show that no groups in India are free of such mixture, the researchers did identify a geographic element. "Groups in the north tend to have more recent dates and southern groups have older dates," said co-first author Priya Moorjani, a graduate student in Reich's lab at Harvard Medical School. "This is likely because the northern groups have multiple mixtures."
"This genetic datatells us a three-part cultural and historical story," said Reich, who is also an associate member of the Broad Institute. "Prior to about 4000 years ago there was no mixture. After that, widespread mixture affected almost every group in India, even the most isolated tribal groups. And finally, endogamy set in and froze everything in place."
"The fact that every population in India evolved from randomly mixed populations suggests that social classifications like the caste system are not likely to have existed in the same way before the mixture," said co–senior author Lalji Singh, currently of Banaras Hindu University, in Varanasi, India, and formerly of the CSIR-Centre for Cellular and Molecular Biology. "Thus, the present-day structure of the caste system came into being only relatively recently in Indian history."*
But once established, the caste system became genetically effective, the researchers observed. Mixture across groups became very rare.
"An important consequence of these results is that the high incidence of genetic and population-specific diseases that is characteristic of present-day India is likely to have increased only in the last few thousand years when groups in India started following strict endogamous marriage," said co–first author Kumarasamy Thangaraj, of the CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.**
Mohan Rao, Director, CSIR-CCMB said, "CCMB's continuing efforts over a decade on this field had helped in understanding the complexity of Indian population history and social structure, such as caste systems."
###
This study was funded by the NIH (GM100233); NSF (HOMINID grant 1032255); a UKIERI Major Award (RG-4772); the Network Project (GENESIS: BSC0121) fund from the Council of Scientific and Industrial Research, Government of India; a Bhatnagar Fellowship grant from the Council of Scientific and Industrial Research of the Government of India; and a J.C. Bose Fellowship from Department of Science and Technology, Government of India.
*, ** Quotes adapted from American Journal of Human Genetics news release.
Genetic evidence shows recent population mixture in India
A new study indicates that population admixture occurred in the pre-caste era, shedding light on our understanding of the history of the present-day Indian populations
2013-08-08
ELSE PRESS RELEASES FROM THIS DATE:
LEC: A multi-purpose tool
2013-08-08
KANSAS CITY, MO—A little-studied factor known as the Little Elongation Complex (LEC) plays a critical and previously unknown role in the transcription of small nuclear RNAs (snRNA), according to a new study led by scientists at the Stowers Institute for Medical Research and published in the Aug. 22, 2013, issue of the journal Molecular Cell.
"We have found that LEC not only has a role in this process—it is like the "Swiss Army knife" of snRNA transcription," says Stowers Investigator Ali Shilatifard, senior author of the study. "LEC does it all." The findings shed new ...
Sanford-Burnham scientists identify key protein that modulates organismal aging
2013-08-08
LA JOLLA, Calif., August 8, 2013 — Scientists at Sanford-Burnham Medical Research Institute have identified a key factor that regulates the autophagy process, a kind of cleansing mechanism for cells in which waste material and cellular debris is gobbled up to protect cells from damage, and in turn, modulates aging. The findings, published in Nature Communications today, could lead to the development of new therapies for age-related disorders that are characterized by a breakdown in this process.
Malene Hansen, Ph.D., associate professor in Sanford-Burnham's Del E. Webb ...
Latino genomes point way to hidden DNA
2013-08-08
Hidden in the tangled, repetitious folds of DNA structures called centromeres, researchers from Harvard Medical School and the Broad Institute have discovered the hiding place of 20 million base pairs of genetic sequence, finding a home for 10 percent of the DNA that is thought to be missing from the standard reference map of the human genome.
Mathematician Giulio Genovese, a computational biologist in genetics at HMS and at the Broad Institute, working in the lab of geneticist Steven McCarroll, HMS assistant professor of genetics and director of genetics for the Stanley ...
Scientists watch live brain cell circuits spark and fire
2013-08-08
Scientists used fruit flies to show for the first time that a new class of genetically engineered proteins can be used to watch nerve cell electrical activity in live brains. The results, published in Cell, suggest these proteins may be a promising new tool for mapping brain cell activity in multiple animals and for studying how neurological disorders disrupt normal nerve cell signaling. Understanding brain cell activity is a high priority of the President's Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative.
Brain cells use electricity ...
A powerful strategy for developing microbial cell factories by employing synthetic small RNAs
2013-08-08
The current systems for the production of chemicals, fuels and materials heavily rely on the use of fossil resources. Due to the increasing concerns on climate change and other environmental problems, however, there has been much interest in developing biorefineries for the production of such chemicals, fuels and materials from renewable resources. For the biorefineries to be competitive with the traditional fossil resource-based refineries, development of high performance microorganisms is the most important as it will affect the overall economics of the process most significantly. ...
Scientists devise innovative method to profile and predict the behavior of proteins
2013-08-08
SAN FRANCISCO, CA and COLLEGE STATION, TX—August 8, 2013—An enzyme is a tiny, well-oiled machine. A class of proteins that are made up of multiple, interlocking molecular components, enzymes perform a variety of tasks inside each cell. However, precisely how these components work together to complete these tasks has long eluded scientists. But now, a team of researchers has found a way to map an enzyme's underlying molecular machinery, revealing patterns that could allow them to predict how an enzyme behaves—and what happens when this process disrupted.
In the latest ...
Kids born small should get moving
2013-08-08
HOUSTON – (Aug. 8, 2013) – Female mice who were growth restricted in the womb were born at a lower birth weight, but were less active and prone to obesity as adults, said researchers from Baylor College of Medicine and the USDA/ARS Children's Nutrition Research Center (CNRC) at BCM and Texas Children's Hospital in a report that appears online in the International Journal of Obesity.
"Given that human studies also show female-specific obesity following early growth restriction," said Dr. Robert Waterland, associate professor of pediatrics – nutrition at BCM, and a member ...
Scientific breakthrough reveals how vitamin B12 is made
2013-08-08
Vitamin B12 is pieced together as an elaborate molecular jigsaw involving around 30 individual components. It is unique amongst the vitamins in that it is only made by certain bacteria. In the early 1990's it was realised that there were two pathways to allow its construction – one that requires oxygen and one that occurs in the absence of oxygen. It is this so-called anaerobic pathway, which is the more common pathway, that proved so elusive as the components of the pathway are very unstable and rapidly degrade.
However, as explained in a paper published by PNAS (Proceedings ...
New forensic technique for analyzing lipstick traces
2013-08-08
Using a technique called Raman spectroscopy, which detects laser light, forensic investigators will be able to analyse lipstick marks left at a crime scene, such as on glasses, a tissue, or cigarette butts, without compromising the continuity of evidence as the sample will remain isolated.
Analysis of lipstick traces from crime scenes can be used to establish physical contact between two individuals, such as a victim and a suspect, or to place an individual at a crime scene.
The new technique is particularly significant for forensic science as current analysis of lipstick ...
Cesareans weaken gut microbiota and increase risk of allergies
2013-08-08
Children who came into the world by Caesarean section are more often affected by allergies than those born in the natural way. The reason for this may be that they have a less diverse gut microbiota, according to a study by universities in Sweden and Scotland.
The researchers have followed gut macrobiota development in 24 children up to the age of two in the Swedish provinces of Östergötland and Småland, nine delivered through Caesarean and 15 delivered naturally, through vaginal birth. They used a type of molecular biology analysis, which gives a broad overview of the ...
LAST 30 PRESS RELEASES:
College commuters: Link between students’ mental health, vehicle crashes
Using sugars from peas speeds up sour beer brewing
Stormwater pollution sucked up by specialized sponge
Value-added pancakes: WSU using science to improve nutrition of breakfast staple
Beyond the gut: A new frontier in IBS treatment by targeting the brain
New spin on quantum liquids: Quasi-1D dynamics in molecular spin systems
Spinal cord stimulation restores neural function, targets key feature of progressive neurodegenerative disease
Shut the nano gate! Electrical control of nanopore diameter
Cutting emissions in buildings and transport: Key strategies for 2050
How parents can protect children from mature and adult content
By studying neutron ‘starquakes’, scientists hope to transform their understanding of nuclear matter
Mouth bacteria may hold insight into your future brain function
Is cellular concrete a viable low-carbon alternative to traditional concrete for earthquake-resistant structures?
How does light affect citrus fruit coloration and the timing of peel and flesh ripening?
Male flies sharpened their eyesight to call the females' bluff
School bans alone not enough to tackle negative impacts of phone and social media use
Explaining science in court with comics
‘Living’ electrodes breathe new life into traditional silicon electronics
One in four chance per year that rocket junk will enter busy airspace
Later-onset menopause linked to healthier blood vessels, lower heart disease risk
New study reveals how RNA travels between cells to control genes across generations
Women health sector leaders good for a nation’s wealth, health, innovation, ethics
‘Good’ cholesterol may be linked to heightened glaucoma risk among over 55s
GLP-1 drug shows little benefit for people with Parkinson’s disease
Generally, things really do seem better in morning, large study suggests
Juicing may harm your health in just three days, new study finds
Forest landowner motivation to control invasive species depends on land use, study shows
Coal emissions cost India millions in crop damages
$10.8 million award funds USC-led clinical trial to improve hip fracture outcomes
University Hospitals Cleveland Medical Center among most reputable academic medical centers
[Press-News.org] Genetic evidence shows recent population mixture in IndiaA new study indicates that population admixture occurred in the pre-caste era, shedding light on our understanding of the history of the present-day Indian populations