Denisovans, A Mysterious Kind Of Ancient Humans, Are Traced To Tibet | KERA News

Denisovans, A Mysterious Kind Of Ancient Humans, Are Traced To Tibet

May 1, 2019
Originally published on May 4, 2019 6:57 am

The jawbone of a little-known form of ancient human has been discovered in western China. Scientists say these people lived as long as 150,000 years ago, and they were part of a group called Denisovans.

The Denisovans are a mystery. Up until now, their only remains — a few bone fragments and teeth — came from a cave called Denisova in Siberia.

In 2010, scientists concluded from those fragments and their DNA that Denisovans were slightly different from us — Homo sapiens — and slightly different from Neanderthals, but that they lived contemporaneously. In short, they were a third kind of human.

The Xiahe mandible was originally found in 1980 in Baishiya Karst Cave. Researchers say the bone is 160,000 years old and came from a Denisovan.
Dongju Zhang/Lanzhou University

What those researchers didn't know in 2010 was that 30 years earlier, a Tibetan monk had found part of a jawbone in a cave on the Tibetan Plateau, home of the Himalayas. He gave it to the Sixth Living Buddha, a holy man there, who passed it on to scientists. They started studying the piece of bone nine years ago. Now they say that it, too, is Denisovan.

"The specimen is much more complete than anything else we know in the Denisova cave," says Jean-Jacques Hublin, from the Max Planck Institute in Germany and a member of a Chinese and European team that studied the jaw and its two remaining teeth.

"It's the first time that Denisovans are identified far away from the Denisova cave," he says.

The bone — half of the lower jaw or mandible — was found in a huge cave almost 11,000 feet up in the plateau. Chinese scientist Dongju Zhang of Lanzhou University in China says these archaic humans "successfully adapted to high-altitude, low-oxygen environments long before the regional arrival of modern Homo sapiens."

She also notes that there were tools and animal bones bearing cut marks in the cave. If those remnants were left by the Denisovans, it means they likely lived there for a while.

But the fact that some Denisovans would have lived in Tibet makes sense. Here's why: When scientists first examined DNA from the Denisovan bones in Siberia, they found many genes that modern humans also have. One of those genes we've inherited, and is common among Tibetans, gives people the ability to live at very high altitudes with low oxygen levels.

A team led by Dongju Zhang (top right in the trench) excavated trenches in Baishiya Karst Cave in 2018.
Dongju Zhang/Lanzhou University

So apparently, some early Denisovans lived on the Tibetan Plateau a long time ago; the jaw is 160,000 years old. They developed the low-oxygen trait, and then at some point passed it on to humans.

"It's in the modern human gene pool because of interbreeding with Denisovans," says Matthew Tocheri, a paleoanthropologist at Lakehead University in Canada, who studies early humans in Asia. "And now this particular jaw that's been identified as Denisovan is actually from the Tibetan Plateau, so it connects these dots."

Tocheri says the discovery reinforces the growing realization that the main river of human lineage was split into numerous tributaries. And some were pretty far off the mainstream, like the 4-foot-tall Homo floresiensis, or Hobbit. It lived as recently as 50,000 years ago on a remote island in Indonesia, but it had numerous apelike characteristics reminiscent of creatures that lived millions of years ago.

"It wasn't that long ago that humans were way more diverse than they were today," says Tocheri, "and we carry on some of that diversity because we ... have some of these genes that survive in us." And sometimes, like the low-oxygen gene, they make us more adaptable.

"Clearly, modern humans have reaped the benefit of these adaptations that they acquired," Tocheri says.

The research on the new find appears in the journal Nature.

Copyright 2019 NPR. To see more, visit https://www.npr.org.
Looking through the Jiangla River Valley at the upper reach of the valley. Ganjia Basin can be seen in the end of the valley.
Dongju Zhang/Lanzhou University

SCOTT SIMON, HOST:

The jawbone of a little-known form of ancient human has been discovered in China. I wonder if he's an ancestor of BJ Leiderman, who writes our theme music. A Buddhist monk found the jawbone. In 2010, scientists began to study it. Now they say it belongs to a human relative that lived as long as 150,000 years ago. NPR's Christopher Joyce reports on what scientists make of it.

CHRISTOPHER JOYCE, BYLINE: The Denisovans are a mystery. Their only remains - a few bone fragments and teeth - were found in a cave called Denisova in Siberia. In 2010, scientists concluded from those fragments and their DNA that Denisovans were slightly different from us, slightly different from Neanderthals, too - in short, a third kind of human. What they didn't know was that 30 years earlier, a Tibetan monk had found part of a jawbone in a cave on the Tibetan Plateau, home of the Himalayas. He gave it to the sixth living Buddha, a holy man there, who passed it on to scientists. They started studying it nine years ago. Now they say it's Denisovan

JEAN-JACQUES HUBLIN: The specimen is much more complete than anything else we know in the Denisova cave.

JOYCE: Jean-Jacques Hublin from the Max Planck Institute in Germany is part of a Chinese and European team that announced the discovery this week.

HUBLIN: It's the first time that Denisovans are identified far away from the Denisova cave.

JOYCE: The bone was found in a huge cave almost 11,000 feet up in the plateau.

HUBLIN: It's a big surprise because most people thought that challenging environments like the high altitudes were colonized only by modern humans like us.

JOYCE: But the fact that some Denisovans lived in Tibet makes sense. Here's why. Modern humans have some Denisovan genes. One of those genes gives people the ability to live at very high altitudes with low oxygen levels. And modern Tibetans have that gene. So apparently, some early Denisovans lived on the Tibetan Plateau. The jaw is 160,000 years old. They developed the low oxygen trait and passed it on to humans.

MATTHEW TOCHERI: It's in the modern human gene pool because of interbreeding with Denisovans.

JOYCE: Matthew Tocheri is a paleoanthropologist at Lakehead University in Canada.

TOCHERI: And now this particular jaw that's been identified as Denisovan is actually from the Tibetan Plateau. So it connects these dots.

JOYCE: Tocheri says the discovery reinforces the idea that the human lineage was like a landscape of parallel streams. And some were pretty far off the mainstream, like the 4 foot tall Homo floresiensis or the hobbit. It lived as recently as 50,000 years ago on a remote island in Indonesia and had numerous primitive ape-like characteristics.

TOCHERI: It wasn't that long ago that humans were way more diverse than they are today. And we carry on some of that diversity because we sort of have some of these genes that survive in us.

JOYCE: The research appears in the journal Nature. Christopher Joyce, NPR News. Transcript provided by NPR, Copyright NPR.