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

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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

Research Yields Possible Blood Test for Cancer

The test was most successful with ovarian cancer, followed by liver, stomach, pancreatic, esophageal, colorectal, lung and breast cancers.

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Scientists have found a way of detecting cancer through blood tests. IANS
Scientists have found a way of detecting cancer through blood tests. IANS
  • Scientists have developed a blood test which can detect cancer
  • This blood test can detect eight types of cancer
  • They have developed a way of detecting DNA which comes specifically from cancer

Scientists at Johns Hopkins University (JHU) are reporting progress in developing a blood test to detect eight types of cancer at an early stage, including some of the most deadly ones that are difficult to detect with existing screening tools.

In a study published Thursday in the journal Science, JHU scientists examined how well their experimental test detected cancer in people already diagnosed with the disease.

Also Read : How broccoli can help keep colorectal cancer away 

This blood test can detect 8 types of cancers. Pixabay
This blood test can detect 8 types of cancers. Pixabay

In blood samples from more than 1,000 patients already diagnosed with cancer, the test detected the cancer in about 70 percent of the subjects.

Nikolas Papadopoulos, a professor of oncology and pathology at Johns Hopkins Sidney Kimmel Cancer Center, said the test is noninvasive.

“All [patients] have to do is give a little bit of blood,” he told VOA. “What we detect is DNA, which is the genetic material that is present in all of our cells, but we have developed a method to detect DNA that comes only from the cancer cells.”

Scientists have been focused on liquid biopsy tests which look for mutated DNA that floats freely in the blood and in cancer-related proteins to try to find cancer before it spreads. They focused on cancers for which there is little or no early-screening process — the ones that are often serious enough to be deadly by the time they are detected.

“That’s one of the tricks that cancer plays on us,” Papadopoulos said. “It grows inside of us and we feel fine until we start having something like a pain or a cough or something like that. And many times, it’s too late.”

Also Read : Alcohol can be linked with seven types of Cancer

This test detects DNA which is specifically formed due to cancer. sites.bu.edu
This test detects DNA which is specifically formed due to cancer. sites.bu.edu

The test was most successful with ovarian cancer, followed by liver, stomach, pancreatic, esophageal, colorectal, lung and breast cancers.

“This study that’s just published, it’s the first step,” Papadopoulos said.

He said a larger study is under way, with a pool of thousands of people. Unlike the earlier study, which dealt solely with patients already known to have cancer, the new group makes up a more representative sample of the general population — that is, most do not have cancer, at least not that has been diagnosed.

“The new study is different in that it simulates what is going to be the population that this test will be applied to,” he said. “And hopefully, we will get good results.” VOA