Wednesday, August 14, 2019

Denisovans: Jawbone Reveals Ancient Human Denisovan Lived in oxygen-starved Himalayas

Denisovans Jawbone

Ancient Human Ancestor – Denisovans

Denisovans, ancient human ancestor, has been revealed by archaeologists, dating 160,000 years back. This is said to be oxygen starved Tibetan Plateau, 11,000 feet above sea level. Research on the genes of the species located in some present people like the Sherpas showed signs of them thriving at high altitudes.

Earlier, it wasunknow how some of the Tibetan natives flourished at these altitudes when the level of the oxygen seemed to be 40% less than that of the sea level.Archaeologists who discovered half a mandible/jaw bone state that the presently non-existent race existed around 100,000 years at a high altitude region.
It was informed that the bone had been located in the year 1980 in a cave in China by a monk before it had been evaluated by researchers. It has been considered to be one of the oldest hominin fossil ever located in the Himalayan region at such a high altitude.

Survive At High Altitudes

It was assumed that Denisovans have interbred with primitive Homo sapiens. Hence their genes are the reason why some types of humans tend to be capable of living at high altitudes.Denisovans DNA samples have been discovered all over Asia stretching right up to Australia and presently in Melanesia.

The Denisovans together with their sub-species, the Neanderthals have been considered to have multiplied with the ancestors of the present generation. The present day Sherpas and Tibetans seemed to have inherited the Denisovans genetic deviations which enabled them to survive at high altitudes.

The cave where the jawbone had been unearthed, Baishiva Karst Cave is said to be situated at an altitude of 10,760 feet. The researchers have not been successful in locating any DNA traces in the fossil though managed to remove proteins from one of the molars.

Archaic Hominins

On scrutiny, it was believed to be that of Denisovans. The research led by Dr Dongiu Zhang, co-leading the research, of Lanzhou University from Gansu province of China had stated that `Archaic hominins occupied the Tibetan plateau in the Middle Pleistocene and had successfully adapted to high altitude, low oxygen environments long before the regional arrival of modern Homo sapiens.

As per the research reported in Nature, the jawbone which was well maintained is said to be tough with very big molars, structures shared by Neanderthals and Denisovans. Researchers were able to date the fossil to at least 160,000 year old, due to the covering of heavy carbonate crust layer. Ancient specimen from Denisova Cave in Siberia seemed to be of the same time era.

Function Related to Fuel-Efficient Car 

Initially a local monk had discovered the Denisovans jawbone in 1980 and had donated the same to the sixth Gung-Thang Living Buddha, a Buddhist Lama who had then passed it to Lanzhou University.

The extinct species of humans, the Denisovans seemed to have lived in Siberia and as far as Southeast Asia. Though the remains of these early humans had only been exposed at one site at the Denisova Cave in the Altai Mountains in Siberia, the DNA analysis indicated that they were widespread.

DNA from the early humans identified in the genomes of modern humans over a large area in Asia, indicated that they once covered an enormous range. According to research it has been revealed that they had established a function related to that of a fuel-efficient car. Their strengths seemed to get more mileage inspite of less oxygen in comparison to that of an average person.

The Sherpas seem to have mitochondria which are miniature rod similar to power plants in cells which have a tendency of being extra-efficient while utilising oxygen. Though the red blood cell count tends to increase at high altitude, it stays below the level where the blood thickens, causing a strain on the heart, resulting in altitude sickness.

Temporary Shelter/Permanent Settlement

Ivory beads and bone were also found in the Denisova Cave with the same deposit layers as the Denisovan fossils, giving some insights on their sophisticated tools and jewellery. DNA analysis in 2010, on a segment of a fifth digit finger bone belonging to a young female, revealed that they belonged to species linked to, though different from the Neanderthals.

Later research indicated that the ancient species of human differed from the Neanderthals towards 470,000 and 190,000 years back. It has puzzled the anthropologist in thinking that the cave could have been utilised as a temporary shelter for these Denisovans or could have been made as a permanent settlement.

A paleoanthropologist at the Natural History Museum in London, Chris Stringer though not involved in the study described the `first use’ of the protein analysis in identifying the Denisovan fossil as a `notable landmark’. In an email to Gizmodo, he explained that it was early days for the research and that they should be alert while the data from the fossil and the relative samples are spare.

Shared Common Ancestor with Neanderthals

However the technique seems promising for charting relationships of fossil hominins where DNA does not seem to be preserved. For Katerina Douka an archaeologist at the University of Oxford not connected with the study, the most exciting aspect of the of the revelation was the location of the new site which was over 3,000 meters above sea level and not the presence of Denisovans outside Siberia. Denisovans during this particular geological era at this altitude seems astonishing according to her.

The discovery fits well with her earlier research. Douka’s team in that study had dated the oldest Denisovan fossils located in Denisova cave to the same era indicated by the Tibetan Plateau fossil.Scientists have found over the past decade, Denisovans teeth together with bone remains, comprising of a portion of a skull. It seems that the Denisovans lived in the cave at intervals from 287,000 years back to 50,000 years ago.

From the DNA analysed, it is presumed that the Denisovans shared a common ancestor with Neanderthals some 400,000 years back. They multiplied with Neanderthals with our species. Presently we find that the people in East Asia, the Pacific Islands, Australia and America tend to have some DNA of the Denisovans.

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