A nearly intact ancient human skull rested at the bottom of a well in Harbin City, Heilongjiang Province, China, for more than 80 years, according to Chris Stringer. According to legend, laborers building a bridge in Japanese-occupied northeastern China uncovered the specimen from the Songhua River’s bed in 1933. The crew foreman understood the worth of the Harbin cranium and did not want it to fall into the hands of the Japanese occupiers, so he stored it away.
“He wrapped it up and tossed it down an abandoned well,” says the narrator. Then, while he was dying roughly 80 years later, he told his grandchildren the story of how he received the skull. They went down to investigate, but it was still down there. “It’s incredible,” says Stringer, a paleoanthropologist at the Natural History Museum in London who studies human origins. The Harbin skull discovers in 2018 after spending more than 146,000 years buried in mud and decades in concealment.
Three years later, on Friday, the first scientific descriptions of the skull, dubbed the “Dragon Man,” were published in a series of three publications in The Innovation, a new journal supported by the Chinese Academy of Sciences. Stringer has been a member of the study team since 2019 and is a co-author on two of the three papers. He describes the cranium as “a fantastically preserved specimen.” “I believe it is one of the most significant discoveries of the previous 50 years.” These research conclusions publish on the same day as similar seismic findings based on partial skull specimens discovered in Israel.
Stringer and his colleagues estimated the skull’s age to be 146,000 years old, putting it in the Middle Pleistocene epoch. The researchers also declare the specimen to be a new species on the human evolutionary tree, stretching from our earliest bipedal primate ancestors to today’s contemporary humans. After the skull’s geographic origin in Heilongjiang, whose name means Black Dragon River, they name this suggested Homo longi, which derived from the Mandarin word for dragon. The researchers believe that H. longi is a more closely connected lineage to modern humans than Neanderthals, our species’ commonly regarded “sister group.”
The scientists evaluated ratios of chemical isotopes found in microscopic layers of sand trapped in the skull’s nasal cavity, as well as percentages of uranium isotopes in the bone itself, which decay predictably over time, to determine the skull’s age. The researchers evaluated the Harbin cranium’s external physical traits, such as the braincase size, facial proportions and angles, and the sole intact molar tooth, to position the specimen in evolutionary history. They then matched those measures to 95 other previously analyzed samples, including other Chinese skull and bone fragments. Stringer and colleagues used a computer model to create a putative phylogenetic tree (a diagram representing evolutionary relationships through time).
Stringer describes it as a “strange blend of traits.” The skull contains a unique combination of archaic traits, such as a prominent brow ridge and broad face, and modern human features, such as more delicate cheekbones. What, above all else, he claims distinguishes the Harbin skull is its size. “It’s enormous. It’s the largest human fossil skull I’ve ever seen.”
However, a larger brain volume does not always imply a closer relationship to modern humans. Even among the study authors, the conclusions reported in the new pieces aren’t unanimous. Stringer prefers to group the newly described Harbin specimen with a previously discovered skull known as Homo daliensis or Dali Man, saying, “I think calling it a different species [from Neanderthal and Homo sapien] is legitimate, but there are different opinions in the research team about what the name of this species should be.” Although the Dali Man skull differs from the Harbin find in specific ways, Stringer finds that variation within a species is acceptable. “In my opinion, [Homo daliensis] should take precedence over Homo longi.”
The designation and positioning of the Harbin cranium as a new human lineage have also sparked debate among experts not involved in the current research.
Shara Bailey, a paleoanthropologist at New York University specializing in early human specimens from the same period as the Harbin skull, says, “We need DNA before we know where this fossil fits in.” Bailey refers to our understanding of the Middle Pleistocene as “the confusion in the middle,” pointing out that many remnants aren’t well preserved and give contradictory information. The Harbin skull, she says, is “an intriguing discovery” because “how often do we receive a cranium as complete as this?” However, he remains doubtful about the findings of the latest study. “Their study of divergence should be regarded with a grain of salt.”
The newly described skull, according to Bailey, “may represent the face of a Denisovan, which is what we’ve been looking for.” Denisovans are an extinct lineage of archaic people who lived between 50,000 and 300,000 years ago in Asia. According to researchers, our knowledge of Denisovans main based on DNA analysis of incomplete bone fragments, such as the Xiahe mandible, with which the Harbin skull shares many similarities. “It’s thrilling in and of itself,” Bailey adds, “because it might be the first time we see the face of this mysterious human group.”
Denisovans, like Neanderthals, overlapped and interbred with modern humans, leaving fragments of their DNA identifiable in modern populations. According to Bailey, Neanderthal DNA founds in a small fraction of European and Asian descent persons. In contrast, Denisovan’s DNA founds in Aboriginal Australians, Papuans, and people of Asian heritage, particularly Melanasians.
According to John Hawks, a paleoanthropologist and professor of anthropology at the University of Wisconsin-Madison, the Harbin skull is a full Denisovan specimen. However, hawks do not rule out alternative options and point out that comparing a jawbone like the Xiahe mandible to this skull, which is missing its lower jaw, has its limitations. The similarities between the two specimens, however, he claims, are considerable. “They’re both missing their third molders,” says the narrator. Both of their second molars are enormous. There are some similarities. As a result, I believe it’s a good bet that these are Denisovans.”
Hawks points out that if the Harbin skull is a Denisovan, the researcher’s detailed examination of the cranium’s physical characteristics does not match the DNA data. Based on their investigation, the experts believe the skull is more comparable to modern people than Neanderthals. Denisovan DNA has revealed that the group has a recent common ancestor with Neanderthals but is more distantly related to modern humans. Hawks and Bailey prefer DNA to trait analysis because traits can diverge, emerge, and shift in non-linear ways, whereas DNA provides a complete picture. According to Stringer, another theory is that all three populations separate simultaneously due to geographic isolation. The typical phylogenetic tree may not be able to define their relationship quickly. “You might have something similar to a three-way split in reality.”
Stringer acknowledges that the Dragon Man could be a Denisovan rather than a new species that he and his colleagues have discovered. He replies, “These are not well-resolved issues.” “I’m not convinced that this is a sister species of Homo sapiens 100 percent of the time. We’ll be looking for further information, so this is just the beginning of our investigation.” Stringer plans to analyze the skull’s interior features, such as the inner ear bones, soon to learn more about how the specimen compares to both Neanderthals and modern humans. He also claims that his colleagues investigate the possibilities of obtaining genetic material from the skull for DNA testing.
According to Stringer, the lineage name and location that the Harbin skull represents are minor elements. “For me, species names are labels that allow us to classify things together, but they aren’t absolute. They’re human-made categories, and nature doesn’t always agree with our tidy ideas.”
Bailey, in a way, agrees. “How you interpret species determines whether it is a separate species or not.” She points out that a species defines reproductive isolation in much of biology, but we know that modern humans interbred with previous lineages. And, whatever you name it, the Harbin cranium’s ancestry did not “evolve” into the Homo sapiens who live in Asia today, according to Bailey. This discovery has no bearing on the fact that our forefathers were Africans.
Even with limited interbreeding between past lineages, modern people have far more genetic and physical similarities than an extinct group. According to Bailey, all apparent variations between people alive are a considerably more recent development than the split of these archaic human lineages. “We are a lot more alike than we are dissimilar.”