Ancient Jaw Found in Tibetan Cave Identified as Denisovan by Proteins

[BillTre]

TL;DR Summary

A ancient jaw found 39 years ago in a Tibetan cave has been identified as that of a Denisovan by analyzing protein preserved in it.

Previously, Denisovans have been identified by their DNA sequence but since the DNA only came from a small distal pinky bone and teeth, their appearance was largely unknown.
Science news article here.
However DNA is not well preserved in many environments, so many potential fossils can not be analyzed in this manner.

Jaw Description:

The jaw's features could be a template for spotting other Denisovans. "Its distinct large molars and premolar roots differ from those of Neanderthals," and the jawbone "is very primitive and robust," says Hublin, who sees a resemblance to a jawbone found off the coast of Taiwan known as the Penghu mandible.

The age of the jaw was determined to be minimally 160,000 years old. This is thought to provide a lot of time for the Denisovans to evolve the high altitude tolerance that Tibetans are thought to have inherited from the Denisovans when they interbred, maybe 40,000 years ago.

 

[jim mcnamara]

Denisovans may have passed on a gene to deal with hypoxia, EPAS1. It assists in regulating hemoglobin levels.
Modern humans in Tibet and some few Han people in China have the gene. The assumption is that the Denisovan people are the source of the gene in modern humans.

https://www.bbc.com/news/science-environment-48107498 - BBC article, popular science.

 

[KenJackson]

I am confused about the date. From the article:

Other team members dated a carbonate crust that had formed on the skull by measuring the radioactive decay of uranium in the carbonate. They got a date of 160,000 years ago ...

Skull? The rest of the article is about one piece of jawbone. Where did the skull come from? And the date is for a "carbonate crust", not the bone. Could it be a crust formed from some other very old material?

Just in the last few thousand years, couldn't a medicine man or witch doctor have used the jaw for some ceremony, applying a layer to it for ceremonial purposes? Or could the carbonate be residue of fuel used to burn the body?

Also, they couldn't get any DNA, but they found collagen in good enough condition to sequence. Are we sure collagen would maintain its consistency that long?

 

[jim mcnamara]

@KenJackson Reasonable questions, all of them. I cannot get to the original article in Science. So, it is hard to give you any answers - what the thread is based on is an article in a semi-professional online magazine, published by AAAS. What you can do is go to a college library and see if you can get a xerox of the original article.

Then, the bibliogprahy and the methods and material discussed in the paper might help a lot. I have done this here on PF to settle some disputes and questions for other topics, but I cannot get to the original paper at the moment. Maybe my search-fu stinks, I don't know.

 

[Ygggdrasil]

Here's the study being discussed:

Chen et al. A late Middle Pleistocene Denisovan mandible from the Tibetan Plateau. Nature 569:409 2019 https://www.nature.com/articles/s41586-019-1139-x

Abstract:

Denisovans are members of a hominin group who are currently only known directly from fragmentary fossils, the genomes of which have been studied from a single site, Denisova Cave1,2,3 in Siberia. They are also known indirectly from their genetic legacy through gene flow into several low-altitude East Asian populations4,5 and high-altitude modern Tibetans6. The lack of morphologically informative Denisovan fossils hinders our ability to connect geographically and temporally dispersed fossil hominins from Asia and to understand in a coherent manner their relation to recent Asian populations. This includes understanding the genetic adaptation of humans to the high-altitude Tibetan Plateau7,8, which was inherited from the Denisovans. Here we report a Denisovan mandible, identified by ancient protein analysis9,10, found on the Tibetan Plateau in Baishiya Karst Cave, Xiahe, Gansu, China. We determine the mandible to be at least 160 thousand years old through U-series dating of an adhering carbonate matrix. The Xiahe specimen provides direct evidence of the Denisovans outside the Altai Mountains and its analysis unique insights into Denisovan mandibular and dental morphology. Our results indicate that archaic hominins occupied the Tibetan Plateau in the Middle Pleistocene epoch and successfully adapted to high-altitude hypoxic environments long before the regional arrival of modern Homo sapiens.

This link should allow you to access the full paper w/o a subscription:
https://rdcu.be/bCG1s

 

[Steelwolf]

While I am not sure it has been looked at or proven though modern genetics testing, but some Tibetan sources posit that they had common ancestors with the Northern Chinese and though Siberia to the Inuit, and that the same types of adaptation to high altitudes gave them the better ability to operate in the arctic. The shorter, broader profile with the adaptions to the colder temps at both high altitude and high latitude. It would be interesting to see comparisons and to see if this is actually traceable..