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Indian-origin scientists find South Asians sharing ancestry with a mysterious population

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Indian-origin
Denisovans were probably dark-skinned, unlike the pale Neandertals.n Image source: sci-news.com

New York: Indian-origin scientists among others have found that many bloodlines around the world, particularly of South Asian descent, may actually be a bit more Denisovan- a mysterious population of hominids.

Denisovans lived around the same time as the Neanderthals- researchers including Indian-origin scientists have revealed.

The team from Harvard Medical School and University of California-Los Angeles (UCLA) has created a world map and also used comparative genomics to make predictions about where Denisovan and Neanderthal genes may be impacting modern human biology.

The analysis also proposes that modern humans interbred with Denisovans about 100 generations after their trysts with the Neanderthals.

Denisovan genes can potentially be linked to a more subtle sense of smell in Papua New Guineans and high-altitude adoptions in Tibetans.

Meanwhile, Neanderthal genes found in people around the world most likely contribute to tougher skin and hair.

Most non-Africans possess at least a little bit Neanderthal DNA.

“There are certain classes of genes that modern humans inherited from the archaic humans with whom they interbred, which may have helped the modern humans to adapt to the new environments in which they arrived,” explained senior author David Reich, a geneticist at Harvard Medical School.

On the flip side, there was negative selection to systematically remove ancestry that may have been problematic from modern humans.

“We can document this removal over the 40,000 years since these admixtures occurred,” Reich added.

Reich and lab members, Swapan Mallick and Nick Patterson, teamed up with previous laboratory member Sriram Sankararaman, assistant professor of computer science at the University of California, Los Angeles for the project.

They found evidence that both Denisovan and Neanderthal ancestry has been lost from the X chromosome as well as genes expressed in the male testes.

The team theorises that this has contributed to reduced fertility in males, which is commonly observed in other hybrids between two highly divergent groups of the same species.

The researchers collected their data by comparing known Neanderthal and Denisovan gene sequences across more than 250 genomes from 120 non-African populations publicly available through the Simons Genome Diversity Project.

The analysis was carried out by a machine-learning algorithm that could differentiate between components of both kinds of ancestral DNA, which are more similar to one another than to modern humans.

The study’s limitation is that it relies on the current library of ancient genomes available.

“We can’t use this data to make claims about what the Denisovans or Neanderthals looked like, what they ate, or what kind of diseases they were susceptible to,” said Sankararaman, first author on the paper. “We are still very far from understanding that.”

The new map of archaic ancestry was published in the journal Current Biology. (IANS)

  • Shriya Katoch

    This is really interesting . The idea that South Asians may have a mix of Denisovan with them is fascinating .

Next Story

Development of Alzheimer’s Disease Not Totally Linked to Genetics: Study

The research team analyzed the gene sequence and the biological age of the body's cells from blood

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Genetics
With additional funding, researchers could further explore the interaction between Genetics and environment in the development of Alzheimer's disease and the impact of environmental factors in delaying the onset of this disorder. Pixabay

The colour of our eyes or the straightness of our hair is linked to our DNA, but the development of Alzheimer’s disease isn’t exclusively linked to Genetics, suggest new research.

In the first study published about Alzheimer’s disease among identical triplets, researchers found that despite sharing the same DNA, two of the triplets developed Alzheimer’s while one did not.

The two triplets that developed Alzheimer’s were diagnosed in their mid-70s, said the paper published in the journal Brain.

“These findings show that your genetic code doesn’t dictate whether you are guaranteed to develop Alzheimer’s,” said Dr Morris Freedman, head of neurology at Baycrest Centre for Geriatric Care.

“There is hope for people who have a strong family history of dementia since there are other factors, whether it’s the environment or lifestyle, we don’t know what it is, which could either protect against or accelerate dementia.”

All three, 85-year-old siblings had hypertension, but the two with Alzheimer’s had long-standing, obsessive-compulsive behaviour.

The research team analyzed the gene sequence and the biological age of the body’s cells from blood that was taken from each of the triplets, as well as the children of one of the triplet’s with Alzheimer’s.

Genetics
The colour of our eyes or the straightness of our hair is linked to our DNA, but the development of Alzheimer’s disease isn’t exclusively linked to Genetics, suggest new research. Pixabay

Among the children, one developed early onset Alzheimer’s disease at age 50 and the other did not report signs of dementia.

The research team also discovered that although the triplets were octogenarians at the time of the study, the biological age of their cells was six to ten years younger than their chronological age.

In contrast, one of the triplet’s children, who developed early onset Alzheimer’s, had a biological age that was nine years older than the chronological age.

The other child, who did not have dementia, of the same triplet showed a biological age that was close to their actual age.

Genetic
Your Genetic code doesn’t dictate whether you are guaranteed to develop Alzheimer’s Disease. Pixabay

“The latest genetics research is finding that the DNA we die with isn’t necessarily what we received as a baby, which could relate to why two of the triplets developed Alzheimer’s and one didn’t,” says Dr. Ekaterina Rogaeva, senior author on the paper and researcher at the University of Toronto’s Tanz Centre for Research in Neurodegenerative Diseases.

“As we age, our DNA ages with us and as a result, some cells could mutate and change over time”.

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With additional funding, researchers could further explore the interaction between genetics and environment in the development of Alzheimer’s disease and the impact of environmental factors in delaying the onset of this disorder. (IANS)