Pular para o conteúdo principal

First hominins on the Tibetan Plateau were Denisovans

First hominins on the Tibetan Plateau were Denisovans

So far, Denisovans were only known from a small collection of fossil fragments from Denisova Cave in Siberia.
Publicada em
Modificada em

A research team now describes a 160,000-year-old hominin mandible from Xiahe in China.Using ancient protein analysis, the researchers found that the mandible's owner belonged to a population that was closely related to the Denisovans from Siberia. This population occupied the Tibetan Plateau in the Middle Pleistocene and was adapted to this low-oxygen environment long before Homo sapiens arrived in the region.

Denisovans—an extinct sister group of Neandertals—were discovered in 2010, when a research team led by Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) sequenced the genome of a fossil finger bone found at Denisova Cave in Russia and showed that it belonged to a hominin group that was genetically distinct from Neandertals. "Traces of Denisovan DNA are found in present-day Asian, Australian and Melanesian populations, suggesting that these ancient hominins may have once been widespread," says Jean-Jacques Hublin, director of the Department of Human Evolution at the MPI-EVA. "Yet so far the only fossils representing this ancient hominin group were identified at Denisova Cave."

Mandible from Baishiya Karst Cave

In their new study, the researchers now describe a hominin lower mandible that was found on the Tibetan Plateau in Baishiya Karst Cave in Xiahe, China. The fossil was originally discovered in 1980 by a local monk who donated it to the 6th Gung-Thang Living Buddha who then passed it on to Lanzhou University. Since 2010, researchers Fahu Chen and Dongju Zhang from Lanzhou University have been studying the area of the discovery and the cave site from where the mandible originated. In 2016, they initiated a collaboration with the Department of Human Evolution at the MPI-EVA and have since been jointly analysing the fossil.

While the researchers could not find any traces of DNA preserved in this fossil, they managed to extract proteins from one of the molars, which they then analysed applying ancient protein analysis. "The ancient proteins in the mandible are highly degraded and clearly distinguishable from modern proteins that may contaminate a sample," says Frido Welker of the MPI-EVA and the University of Copenhagen. "Our protein analysis shows that the Xiahe mandible belonged to a hominin population that was closely related to the Denisovans from Denisova Cave."

Primitive shape and large molars

The researchers found the mandible to be well-preserved. Its robust primitive shape and the very large molars still attached to it suggest that this mandible once belonged to a Middle Pleistocene hominin sharing anatomical features with Neandertals and specimens from the Denisova Cave. Attached to the mandible was a heavy carbonate crust, and by applying U-series dating to the crust the researchers found that the Xiahe mandible is at least 160,000 years old. Chuan-Chou Shen from the Department of Geosciences at National Taiwan University, who conducted the dating, says: "This minimum age equals that of the oldest specimens from the Denisova Cave".

"The Xiahe mandible likely represents the earliest hominin fossil on the Tibetan Plateau," says Fahu Chen, director of the Institute of Tibetan Research, CAS. These people had already adapted to living in this high-altitude low-oxygen environment long before Homo sapiens even arrived in the region. Previous genetic studies found present-day Himalayan populations to carry the EPAS1 allele in their genome, passed on to them by Denisovans, which helps them to adapt to their specific environment.

"Archaic hominins occupied the Tibetan Plateau in the Middle Pleistocene and successfully adapted to high-altitude low-oxygen environments long before the regional arrival of modern Homo sapiens," says Dongju Zhang. According to Hublin, similarities with other Chinese specimens confirm the presence of Denisovans among the current Asian fossil record. "Our analyses pave the way towards a better understanding of the evolutionary history of Middle Pleistocene hominins in East Asia."

FONTE: Phys.org, First hominins on the Tibetan Plateau were Denisovans

Postagens mais visitadas deste blog

Pesticide exposure causes bumblebee flight to fall short

Pesticide exposure causes bumblebee flight to fall short Bees exposed to a neonicotinoid pesticide fly only a third of the distance that unexposed bees are able to achieve. CMisteriosBlog Publicada em 2019-04-30 Modificada em 2019-04-30 Flight behaviour is crucial for determining how bees forage, so reduced flight performance from pesticide exposure could lead to colonies going hungry and pollination services being impacted. Foraging bees are essential pollinators for the crops we eat and the wildflowers in our countryside, gardens and parks. Any factor compromising bee flight performance could therefore impact this pollination service. A study by Imperial College London researchers, published today in the journal Ecology and Evolution, reveals how exposure to a common class of neurotoxic pesticide, a neonicotinoid, reduces individual flight endurance (distance and duration) in bumblebees. The study shows that b

Meet Callichimaera perplexa, the platypus of crabs

Meet Callichimaera perplexa, the platypus of crabs The crab family just got a bunch of new cousins—including a 95-million-year-old chimera species that will force scientists to rethink the definition of a crab. CMisteriosBlog Publicada em 2019-04-27 Modificada em 2019-04-27 An international team of researchers led by Yale paleontologist Javier Luque announced the discovery of hundreds of exceptionally well-preserved specimens from Colombia and the United States that date back to the mid-Cretaceous period of 90-95 million years ago. The cache includes hundreds of tiny comma shrimp fossils, several true shrimp, and an entirely new branch of the evolutionary tree for crabs. The most intriguing discovery, according to the researchers, is Callichimaera perplexa, the earliest example of a swimming arthropod with paddle-like legs since the extinction of sea scorpions more than 250 million years ago. The name de