Goodbye to the Dragon Man mystery: Ancient proteins suggest the skull belonged to a Denisovan

For decades, the Harbin cranium fossil has been one of the most discussed finds concerning humans. With its giant size and unique characteristics, it attracted a lot of scientists who were unable to decide exactly where this fossil belonged within the evolutionary timeline. The Harbin cranium fossil also went by the nickname "Dragon Man" due to its unusualness. At least some scientists believed that this fossil represented an entirely new species that they classified under Homo longi, whereas others considered that it could belong to a previously unknown Denisovan group.

The new molecular evidence seems to change the discussion considerably now. According to the researchers, ancient proteins obtained from the skull and mitochondrial DNA extracted from dental calculus prove that the Harbin fossil belonged to the Denisovan group of ancient humans.

Ancient proteins revolutionize the discussion


It should be noted that the Harbin cranium fossil has been known for a very long time before the recent discovery was made. The fossil gained global popularity only in 2021 when researchers presented their findings regarding it. In addition, according to a publication in The Innovation, the specimen represented an independent lineage of humans from the Middle Pleistocene era.

Indeed, back then, there were no DNA sequences, only anatomical classifications. Fossil anatomies of ancient humans across Asia and Europe were studied and compared with the Harbin specimen. However, using only such techniques resulted in uncertainties. As a result, the Harbin fossil remained one of the subjects of debate within the scientific community.

Ancient protein sequencing proved to be the most significant breakthrough yet. According to a study published in Science, ancient protein sequencing was successfully applied to the Harbin cranium. This resulted in identifying 95 different endogenous proteins in the Harbin sample. Among those proteins, there were three that contained amino acids specific to Denisovans.

Notably, while other fossils are mostly fragmented remains, the Harbin fossil was almost intact. Moreover, this meant that this specimen could be described as Denisova 3, one of the best-studied samples from Siberia. As mentioned by Nature, the discovery marked the first time Denisovan genetics were connected to an identifiable face and skull anatomy.

Denisovan DNA found in tooth plaque provided additional support

A study featured in the journal Cell provided another line of scientific support. The scientists extracted mitochondrial DNA belonging to the Denisovans from the dental calculus found on the Harbin fossil. As defined by Nature, dental calculus refers to hard deposits of calcified dental plaque.

The mitochondrial DNA sequence matched known Denisovan genetic variants, as well as previously documented lineages in Denisova Cave. This was significant because the DNA evidence independently supported the results of the earlier protein analysis. Two distinct approaches were now leading the researchers to the same conclusion about the Harbin skull. The successful extraction of mitochondrial DNA via dental calculus also paved the way for studying fossils using alternative means.

The discovery extended the Denisovan narrative

Until the recent findings, Denisovans had been linked to scattered fossils from Siberia and Tibet only. However, the Harbin skull hinted at a larger geographical footprint of the Denisovans, which went beyond Siberia. According to Cell, the Denisovans had occupied a more widespread territory in Asia than previously thought in the Middle Pleistocene.

This greater diversity affects interpretations made about other fossils found in East Asia and classified differently. The Harbin skull becomes an important reference since scientists have something more than just anatomy to compare with. Molecular characteristics are also taken into account. The Harbin skull could provide new insights into ongoing debates concerning several mysterious fossils of prehistoric people found on the Asian continent.

The fossil already had a fairly accurate timeline

An earlier direct dating of the Harbin skull indicated that the specimen was older than 146 thousand years. That means that it was formed in the time interval known as the Middle Pleistocene epoch. As a consequence of its rather well-preserved condition and clear molecular identification, the Harbin skull became one of the most valuable findings of Denisovans ever made.

Nature Ecology & Evolution called this finding a landmark case of anatomical, protein, and genetic research applied to fossils.

The debate still has some open points

Despite all the scientific evidence linking Harbin people with Denisovans, there are still some issues under discussion. There is also much discussion about whether the fossil deserves to retain its classification as a separate species Homo longi, or if it should be considered a member of the already known Denisovan lineage.

However, one thing that is no longer up for discussion is what Dragon Man stands for in paleontology. The Harbin skull has ceased to be a mere unusual fossil, given the nickname due to a lack of proper scientific explanation of its origin.