China Focus: Scientists link nearly complete skull to humans' Denisovan relative

BEIJING, June 18 (Xinhua) -- For fifteen years, scientists had grappled with a fundamental mystery about Denisovans, human beings' ancient cousins. They wondered what Denisovans looked liked. The answer to this question held special significance for East Asian and Oceanian communities, who carry distinct traces of Denisovan DNA.

Now, two landmark studies published Wednesday in Science and Cell, respectively, present molecular evidence confirming that a remarkably preserved 146,000-year-old hominin skull, discovered near Harbin in northeast China, represents a definitive Denisovan fossil.

A research team, led by members from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) under the Chinese Academy of Sciences, has for the first time found that the Harbin cranium is linked to the early Denisovan lineage from Siberia -- resolving a question that had persisted since Denisovans were first identified through ancient DNA in 2010.

Denisovans are an extinct group of archaic humans named after the Denisovan Cave in Siberia where they were first discovered.

The Harbin fossil, classified as a new species named "Homo longi" after the Chinese mythological creature "loong," exhibits striking morphological parallels with known Denisovan remains, research efforts lead by the IVPP members reveal.

Prior to this discovery in northeast China, Denisovan fossils were limited and fragmentary, complicating the understanding of their morphology and evolutionary history.

A previous study published in the journal Nature reported a new hominin rib specimen unearthed in the northeastern part of the Qinghai-Xizang Plateau, dating back approximately 48,000 to 32,000 years ago.

The IVPP team, notably, developed a new method to identify human populations based on ancient proteins, and managed to retrieve host mitochondrial DNA (mtDNA) from the dental calculus of the cranium found near Harbin, capital of Heilongjiang Province.

The team identified 20,455 peptides -- yielding the highest-quality ancient hominin proteome data to date, with an 11-fold increase in peptide coverage over previous contemporaneous fossil analyses.

The results confirmed that the Harbin individual belongs to an early mtDNA lineage of Denisovans, suggesting a wide distribution from Siberia to northeast China during the late Middle Pleistocene.

The two studies done by the IVPP team reveal the relatively complete skull morphology of Denisovans, and provide important references for identifying other ancient human fossils in East Asia that may belong to the Denisovan lineage, said the researchers.

Also, they raise new questions -- Did this early lineage disperse further south in China? And how did it interact with other archaic human populations in China? ■