For decades, fishermen sailing off the coast of Taiwan have occasionally discovered bones from other large mammals that the bones of elephants, buffaloes and other large mammals lived tens of thousands of years ago.
However, in 2010, Taiwanese paleontologists were presented with a particularly strange discovery. This fossil looks like half the jaw of a gorilla. Scientists have been baffling it ever since.
The mystery of the underwater jaw has now been solved. On Wednesday, a team of researchers announced it belongs to Denisovan, a member of the mystical human lineage associated with the Neanderthals. This finding greatly expands the range of well-identified denisoba fossils previously known from Siberia and Tibet.
“Indeed, Denisovan was east all the way to the coast,” says Frido Welker, a molecular anthropologist and author of the new study.
Chun-hsiang Chang, a paleontologist at the National Museum of Natural Sciences of Taiwan, first learned the jaws from a private collector in 2010. After examining it, he could quickly say that it does not belong to a gorilla. Gorillas and other apes have U-shaped jaws. Instead, the fossil jaws were angled outward from the jaw, just like ours.
However, the jaws were missing the prominent jaws seen in humans today. “At the time, I thought it looked human, but not modern-day human,” Dr. Chang said. “I thought it was very important, so I pushed the private collector to lend it to my museum.”
Over the next five years, Dr. Chang studied jaw anatomy, working with an international group of scientists. Its shape resembles the jaws of extinct relatives of humans known to have lived in Asia for over a million years. However, Penghu 1 also had distinctive features, including large teeth.
Determining the age of Penguo 1 was also a challenge, as we were not sure exactly where Dr. Chang came from on the seabed. He and his colleagues analyzed the chemistry of the jaw and discovered that it resembles that of fossils of hyena species that evolved in East Asia about 400,000 years ago.
At that time, Taiwan was separated from the mainland by water. However, 190,000 years ago, sea levels fell sufficiently to create an overpass that lasts until 130,000 years ago. The ocean rose again until 70,000 years ago. This continued until 10,000 years ago when another overpass formed. Dr. Chang and his colleagues believe that one Penga lived in one of these low sea level periods.
One possibility was that Penghu 1 belonged to a mysterious group of humans called Denisovans. Researchers discovered Denisovan in 2010 while examining fossils from the Siberian Denisova Cave. The bones of teeth and fingers contain ancient DNA with abnormal mutations, revealing previously unknown human strains.
Subsequent research shows that Denisovans, Neanderthals and modern people share common ancestors who lived in Africa about 600,000 years ago. The Neanderthal and Denisovan ancestors migrated from Africa, and then these two lineages split about 400,000 years ago. The Neanderthals spread to Europe in the west.
Denisovan's spread was difficult to chart. For years, the only known denisova fossils have been teeth and bone fragments found in Denisova caves. However, the appetite clue comes from living humans. In East Asia and the Pacific, many people today have small amounts of Denisovan DNA. This suggests that before its extinction, Denisovan must have bred with East Asian homo sapiens and lived well beyond Siberia.
Dr. Chang and his colleagues noticed that the teeth on the Penguo 1 jaw resemble the teeth in the Denisova Cave. But those clues weren't enough to link them. They searched DNA in their jaws, but found nothing. The results were not surprising given that the Penghu 1 fossils had been sitting on the seabed for thousands of years.
After Dr. Chang's team published their analysis in 2015, Penghu 1 became an even more enigmatic, human-like fossil at the museum. “Our research was stagnant,” Dr. Chan said.
Over the next few years, Dr. Welker and other researchers have pioneered ways to recover ancient proteins from fossils. It has been revealed that even if a fossil loses all its DNA, it could still retain fragments of protein.
Using such methods, Dr. Welker studied the 160,000-year-old jaws found in a high-altitude cave in Tibet. In 2019, the team reported that Tibetan fossils contained fragments of ancient collagen and other proteins.
These resemble modern human proteins, but also differences indicating that the jaw belongs to Denisovan.
With that discovery, Dr. Welker searched other Asian fossil scientific literature that resemble Tibetan jaws that could be tested for proteins.
“That's when the lower jaw of the penguin comes on my radar,” he said.
Both Tibetan and Taiwanese jaws had very large teeth. Dr. Welker and his colleagues reached out to Dr. Chan. In 2023, Dr. Chang and his team flew to Copenhagen with their jaws. The analysis of the results revealed protein fragments that were only available from denisovan.
“Since the first publication of Peng's lower jaw, many of us thought it might be Denisovan, mainly based on being in the right place at the right time,” said Bens Viola, a paleontologist at the University of Toronto, who was not involved in the study. “But of course, assumptions are assumptions and we need actual data to validate them.”
Another clue came from fragments of enamel protein in the teeth. Modern humans carry enamel genes to the X chromosome, while men carry slightly different enamel genes to the Y chromosome. Denisovanjoe was carrying the Y-chromosome version, indicating that she belonged to male adults.
The two Denisovan jaw big anatomy may turn out to be a hallmark of male Denisovan. Women's Denisovan may have a thinner anatomy, but scientists will need more evidence to know for sure.
The discovery of other denigobus fossils could expand the scope of humanity. In 2022, researchers discovered a 160,000-year-old teeth in a Laos cave that closely resembles the teeth of the chin of Denisovan in Tibet. Anyone who lived there would have had to survive in the tropical forests far from Siberia.
However, Laos' teeth do not contain DNA, and the protein fragments did not clarify the type of human it was born in. However, the cave and neighbors still retain many teeth that have not been fully analyzed. And other traces of Denisovan may not have been found in the museum yet.
But so far evidence reveals that Denisovan can thrive for thousands of miles and in a variety of environments. Janet Kelso, paleontologist at the Max Planck Institute for Evolutionary Anthropology, was impressed by the difference between the Penghu 1 protein and the protein found in Tibet. As Denisovan expanded throughout the environment, they adapted to each location and developed into genetically distinct populations.
“There's still a lot to learn about Denisovan,” she said.
