Who of us have Neanderthal, Denisovan DNA?

FILE – Friday, March 20, 2009 file photo shows a reconstruction of a Neanderthal man, left, and the woman at the Neanderthal museum in Mettmann, Germany. (AP Photo/Martin Meissner)

A lot of people all over the world have more Denisovan DNA than previously thought, which has contributed to their sense of smell and the ability to thrive at high altitude, according to a study released Monday.

Researchers know that modern man with an origin outside of Africa have inherited to 2.1 percent of their DNA from Neanderthals. But less was known about the Denisovans, who are thought to have common origin with the Neanderthals and account for up to 5 percent of the DNA in some of the present day populations.

The last work of a research team at Harvard Medical School and UCLA, developed a map of the world of ancient DNA. In addition, they found that populations of the Pacific population had the highest percentage of old DNA 2 percent Neanderthal and 5 percent Denisovan – while the South Asians had more Denisovan DNA 0.1 percent in sherpas than expected. That increases the possibility of an unknown crossing events.

Western Europeans are the least likely of all non-Africans have Neanderthal or Denisovan DNA, while the Africans have almost none.

Related: DNA of the mysterious “Denisovans’ helped modern humans to survive

“It’s a very comprehensive look at how modern humans evolved, how we got to where are today,” UCLA Sriram Sankararaman, a co-author of the study which appeared in Current Biology, told “You should be able to understand that our interaction with these archaic populations. These crosses are events with very different genes of modern humans, an important question for us in human genetics is to find out what is the influence of these genes.”

Researchers also found the genomic DNA has benefited from the modern man, in good and bad ways – building on earlier research that, according to Live Science, found Denisovan DNA reinforces the modern humans’ immune system and helped them to survive.

Denisovan genes were found to contribute to a more subtle sense of smell in Papua New guinea (png) and has contributed to adjustments to high altitude in Tibetans. Neanderthal genes probably contribute to the tighter skin and hair.

“There are certain classes of genes that modern humans inherited from archaic humans with whom they have a bastard, which may have contributed to the modern man to adapt to the new environment in which they arrived,” David Reich, a geneticist at Harvard Medical School and the Broad Institute and a co-author on the paper, said in a statement. “On the other side, there was a negative selection for the systematic removal of ancestors who may have problems on the field of the modern man. We can take this document through the 40,000 years, since these additives has occurred.”

Related: Prehistoric tooth reveals surprising details about the long lost human ‘cousins’

The most obvious downside to the take over of the old DNA, the researchers found, is the potential for increased infertility – a common problem when species are crossed. As a result, the researchers found evidence that both the Denisovan and the Neanderthal lineage disappeared from the X-chromosome, as well as genes expressed in the testes.

“We see a lot less in comparison with the rest of the genome,” Sankararaman said.

“You go along the genome and there is an X-chromosome or genes that are expressed in the testes. In short, these parts of the genome have less Neanderthal or Denisovan,” he said, adding that “there was very strong pressure to remove the bad copies of these genes.”

Evolutionary geneticist Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, that has demonstrated that Neanderthals and humans first mated 50,000 years ago, praised the study.

Related: Neanderthal woman’s genome reveals unknown human lineage

“I think this is a very nice study. It is especially interesting that, just as the genetic interactions with the Neanderthals in Europe and west Asia seem to be numerous and contributed a number of important gene variants for the current people, in east and south-east Asia, similar things seem to have gone with the Denisovans,” said Pääbo via e-mail.

“It is cool that the Neanderthals and the Denisovans are not completely extinct. s of them live on in the people today,” he added.

The researchers collected their data by comparing with known Neanderthal and Denisovan gene sequences in more than 250 genome of 120 non-African population is publicly available through the Simons Genome Diversity Project. The analysis was performed by a machine learning algorithm that can distinguish between the components of both types of ancestral DNA, which are more similar to each other than to modern humans.

While they can learn much from these crosses, the researchers cautioned against drawing any conclusions on the basis of the DNA about the movement of the population or of the possible attributes that are left behind by our ancestors.

“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 prone to,” Sankararaman said. “We are still far from understanding.”

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