A set of 47 teeth discovered by researchers in a Chinese cave could take a bite out of the conventional timeline of human migration. According to a new study, the ancient fossils suggest Homo sapiens left Africa at least 20,000 years earlier than previously thought.

A new study published Wednesday in the scientific journal Nature could rewrite the conventional timeline of early human migration. The study’s authors reported that they discovered a set of 47 fossilized human teeth embedded in the floor of a massive limestone cave system in the Daoxian region of southern China. Along with the teeth, they found the remains of hyenas, extinct giant pandas and dozens of other animal species but no stone tools, which suggests that the humans did not live in the cave but were hauled there by predators.

Geographical location and interior views of the Fuyan Cave, Doaxian with dating sample (lower left), plan view of the excavation area with stratigraphy layer marked (center), the spatial relationship of the excavated regions and researcher finding human tooth (right). (Credit: Y-J Cai, X-X Yang, and X-J Wu)
Geographical location and interior views of the Fuyan Cave, Doaxian with dating sample (lower left), plan view of the excavation area with stratigraphy layer marked (center), the spatial relationship of the excavated regions and researcher finding human tooth (right). (Credit: Y-J Cai, X-X Yang, and X-J Wu)

María Martinón-Torres, a paleoanthropologist at the University College London and a co-leader of the study, said on a Nature podcast she had no doubt the teeth found inside Hunan Province’s Fuyan Cave came from Homo sapiens due to their small size, thin roots and flat crowns. Their morphology matched those of both ancient and present-day humans. What was a surprise, however, was just how ancient those teeth were. “They really look modern, but they are very old,” she told Nature. “And they are very old also particularly when we take into account that they were found in China.”

Since the fossilized teeth lacked any radioactive carbon, the researchers instead dated the calcite deposits under which they were sealed. Using uranium dating, the scientists determined the cave’s stalagmites to be 80,000 years old, which meant anything underneath needed to be older. Radioactive dating of the menagerie of animal fossils inside the cave confirmed they came from the same time period—the Late Pleistocene Era.

Human upper teeth found from the Fuyan Cave, Daoxian. (Credit: S. Xing)
Human upper teeth found from the Fuyan Cave, Daoxian. (Credit: S. Xing)

Researchers said the teeth they discovered could be as many as 120,000 years old. If the dating is correct, it challenges the conventional scientific thought that Homo sapiens first emerged in Africa around 200,000 years ago but did not move around the globe until a great migration that began approximately 60,000 years ago. “This is stunning, it’s major league,” University of Oxford archaeologist Michael Petraglia, who was not involved in the project, told Nature. “It’s one of the most important finds coming out of Asia in the last decade.”

Although traces of modern humans dating back approximately 100,000 years have been discovered outside of Africa, such as those found in the Skhul and Qafzeh caves in Israel, most scientists believed they were connected to failed migrations. “This demonstrates it was not a failed dispersal,” Petraglia told Nature. “This is a rock-solid case for having early humans—definitely Homo sapiens—at an early date in eastern Asia.”

Human lower teeth found from the Fuyan Cave, Daoxian. (Credit: S. Xing)
Human lower teeth found from the Fuyan Cave, Daoxian. (Credit: S. Xing)

The dating of the teeth also suggests modern humans were present in southern China between 30,000 and 70,000 years before they appeared in Europe, although it is considerably further from the horn of Africa. Martinón-Torres postulates the frigid climate of the Ice Age and the presence of Neanderthals in Europe may have driven early humans east to the warmer climes and emptier lands of Asia.

Some researchers are taking a cautious approach to the new study. Jean-Jacques Hublin, a paleoanthropologist at Germany’s Max Planck Institute for Evolutionary Anthropology, notes some of the teeth have visible cavities, which is uncommon in human teeth more than 50,000 years old. “It could be that early modern humans had a peculiar diet in tropical Asia,” he told Nature. “But I am pretty sure that this observation will raise some eyebrows.”

“This is just the tip of the iceberg,” Petraglia told Nature. “There’s a lot more work that needs to be done.”

Martinón-Torres says the research team will more closely examine the cavities as well as any patterns of tooth wear to learn more about the diets of the early humans. There are many other questions to answer as well, she says. “We really have to understand the fate of this migration. We need to find out whether it failed and they went extinct or they really did contribute to later people,” she told the BBC. “Maybe we really are descendants of the dispersal 60,000 years ago—but we need to re-think our models. Maybe there was more than one ‘Out of Africa’ migration.”