The fossilised remains of an early human cousin found in the mountains of Tibet proves mankind adapted to live at high altitude far earlier than previously thought, scientists said Wednesday.

A jawbone dating from at least 160,000 years ago of a Denisovan -- a now-extinct branch of humanity -- is the first of its kind discovered outside of southern Siberia, and experts believe it holds the key to understanding how some modern-day humans have evolved to tolerate low-oxygen conditions.

Contemporaries of the Neanderthals -- and like them, possibly wiped out by anatomically modern man, Homo sapiens -- the Denisovans first came to light a decade ago.

Their existence was determined through a piece of finger bone and two molars unearthed at the Denisova Cave in southern Siberia's Altai Mountains and dated to some 80,000 years ago.

But the new remains -- discovered in passing by a local monk nearly thirty years ago -- has led researchers to conclude that Denisovans were far more numerous, and far older, than previously thought.

"To have beings, even if a little archaic, living at 3,300 metres (11,000 feet) on the Tibetan plateau 160,000 years ago.... That's something that no one could have imagined until today," said Jean-Jacques Hublin, director of the Max Planck Institute's Department of Human Evolution.

The bone, found in the Baishiya Karst Cave in Xiahe, China, was donated by the monk to a local museum, before scientists set about analysing its composition. It was so old no DNA could be extracted.

But Hublin and his team used the latest protein analysis to date one of its teeth and to link it genetically to Denisovan specimens found in Siberia.

"From my point of view it's confirmation of a working hypothesis I've had for a while: Nearly all Chinese and east Asian (hominim) fossils between 350,000-50,000 years ago are probably Denisovan," said Hublin, lead author of the study published in Nature.

- 'Extraordinary' -

A recent research paper suggested that humans only reached the Tibetan plateau -- a vast area of mountainous terrain north of the Himalayas -- around 40,000 years ago.

"Here we have something that's four times older," said Hublin. "It's absolutely extraordinary."

The jawbone discovery also solves a riddle that has troubled anthropologists for years.

In 2015 researchers found that ethnic Tibetans and Han Chinese living at altitude had buried in their genetic code an unusual variant of a gene, EPAS1, which regulates haemoglobin, the molecule that hauls oxygen around the blood.

At high altitude, common variants of the gene overproduce haemoglobin and red blood cells, causing the blood to become thick and sludgy -- a cause of hypertension, low birthweight and infant mortality.

But the variant found in Tibetans increases production by much less, thus averting hypoxia problems experienced by many people who relocate to places above 4,000 metres in altitude.

The mutation is nearly identical to that found in the DNA of Denisovans discovered in Siberia -- at an altitude of less than 700 metres.

"That was something that no one really understood, because the Denisovans weren't known to live at altitude, so they didn't really need that gene to survive," said Hublin.

"Now we know why. It's not the DNA from Denisovans from (Siberia), it's the DNA from the Denisovans of Tibet."

Sense of smell differs between people, can shift with small genetic changes
Washington DC (UPI) May 01, 2019 - New research suggests just a small change to a single olfactory gene can alter how a person perceives odors.

The study, published this week in the journal PNAS, suggests different smells can be experienced a variety of ways by different people.

By studying the effects of olfactory gene tweaks on the experience of smell, scientists can gain a better understanding of how the olfactory system works.

"By taking advantage of the natural variation in the olfactory receptor family, we can gain crucial insight into how the olfactory system works and how differences in this system may impact food choice, nutritional health, and overall well-being," Casey Trimmer, a geneticist at the Monell Chemical Sense Center, said in a news release.

Every human nose hosts 400 different types of sensor proteins, or olfactory receptors. Different types of neurons are activated by a variety of molecules, and different smells activate an array of neurons. As a result, the brain must process activation patterns, or signatures, across the full spectrum of receptor types.

Different signature patterns correspond to different smells, as well as how they're interpreted -- strong or weak, foul or pleasant. This complex coding system is still not well understood by scientists.

"We still know very little about how olfactory receptors translate information from an odor molecule into the perception of an odor's quality, intensity, and pleasantness," said Joel Mainland, an olfactory neurobiologist at Monell. "By examining how variation in an olfactory receptor gene changes odor perception, we can begin to understand the function of each receptor. This in turn will help us learn how the receptors work together so that we can decipher the olfactory code and digitize olfaction."

For the new study, scientists surveyed participants to rate the smell experience for 70 different odors. Researchers collected DNA samples from each participant and identified differences among the 400 olfactory receptor genes.

"We used people's genes to identify who has a broken form of a given receptor and compared their odor perception to that of individuals having the more functional version of that receptor. Is the odor less strong? Is it more pleasant? Is it both?" said Trimmer

Scientists were surprised to find a single gene difference could inspire differences in participants' perception of the same odor.

"Because most odors activate several receptors, many scientists thought that losing one receptor wouldn't make a difference in how we perceive that odor. Instead, our work shows that is not the case and changes to a single receptor can make a big difference in how you perceive an odor," said Mainland.

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Human ancestors were 'grounded,' new analysis shows
New York NY (SPX) May 01, 2019
African apes adapted to living on the ground, a finding that indicates human evolved from an ancestor not limited to tree or other elevated habitats. The analysis adds a new chapter to evolution, shedding additional light on what preceded human bipedalism. "Our unique form of human locomotion evolved from an ancestor that moved in similar ways to the living African apes - chimpanzees, bonobos, and gorillas," explains Thomas Prang, a doctoral candidate in New York University's Department of Anthrop ... read more