Junix imperialis, an extinct gibbon discovered in a royal Chinese tombSamuel Turvey / ZSL

When Samuel Turvey found a drawer labelled “gibbon,” he knew he had hit the jackpot. But what he found inside was better than he could have hoped for.

Yes, it was a gibbon, or rather the remains of one—parts of its face, jaw, and arm. These fragments were enough for Turvey to show that the animal belonged to a new species of gibbon, distinct from the 20 that live today, and all the ones that we know of from prehistory. And it had been discovered in, of all places, an ancient royal Chinese tomb.

Of all the apes, gibbons are the smallest, the most vocal, and the most at home in trees. Their unique wrists are similar to the ball-and-socket joints in our shoulders, allowing them to swing through branches at up to 34 miles an hour. In recent history, seven species swung through Chinese forests, but two have disappeared within the last few decades, and the rest are all critically endangered. One, the Skywalker gibbon, was only discovered last year. Another, the Hainan gibbon, is the rarest ape alive, with just 26 individuals clinging to existence in a small patch of forest. Between all the remaining species, there are probably no more than 1,500 individuals left.

It wasn’t always like this. Gibbons once abounded in China, and were culturally significant for centuries. Their haunting songs were associated with homesickness, and their supposedly “noble” qualities made them symbols of scholar-offiicals or junzi. “For a long time, I’ve been aware that gibbons are known from historical records across a large area of China,” says Turvey. “But no one knew what species these extinct populations belonged to.” He tried to find out by visiting the Shaanxi Provincial Institute of Archaeology in 2009, and examining specimens that had been collected from the ancient capital city of Xi’an. That’s when he found the gibbon drawer. “It was definitely a Eureka moment,” he says.

The bones had come from a tomb that archaeologists suspect belonged to Lady Xia, the grandmother of China’s first emperor Qin Shihuang. She had been buried with several animals, including leopards, lynxes, black bears, cranes, and at least one gibbon. But, Turvey says, “Shaanxi is a huge distance from any of China’s surviving gibbon populations.” That immediately made him suspect that this particular gibbon “could be something extremely interesting.”

The gibbon’s bones might still contain DNA that could easily settle the question of its identity, but extracting it would involve destroying or damaging the precious specimens. Instead, Turvey teamed up with Helen Chatterjee, a self-described gibbonologist at University College London, to scan the bones and compare their features with those of other species. They showed that the animal in the drawer was an outlier, and distinct from known gibbons. The differences are “subtle to the naked eye,” says Chatterjee, but thanks to a quantitative 3-D analysis of the specimen, “we can see that they are significant.” They named the animal Junzi imperialis.

Sadly, it no longer exists. Historical accounts tell of gibbons being caught near Xi’an into the tenth century, and surviving in the local surrounding province into the 18th. “But there is no evidence that gibbons have lived in the region where this specimen was found for many hundreds, if not thousands, of years,” says Chatterjee. Junzi lived in China’s center, and the closest gibbons now reside more than 750 miles away in the far southwest. “Central China has no truly remote corners left in which remnant gibbon populations might still be hiding,” says Turvey.

On the basis of one specimen, it’s impossible to say why Junzi disappeared. But it’s clear that gibbons as a group have receded from China’s forests as the country’s massive human populations have expanded. Even compared to other primates, gibbons are extremely vulnerable. They’re specialized for life in the forest canopy; as trees are felled, gibbons become isolated in small and precarious pockets of forest. To compound the risk, they are also actively hunted for food and traditional medicine. “This study suggests that unsustainable hunting may have been driving gibbons to extinction well before large-scale forest clearing started to devastate modern gibbon populations,” says Susan Lappan, an anthropologist at Appalachian State University.

Until now, “it was thought that apes and most other primates have been relatively resilient to past human pressures,” says Turvey, and had only recently become endangered. But Junzi’s discovery suggests that at least some ape species were blinking out of existence further back in human history than suspected. There could be many other vanished gibbons out there and we wouldn’t know it, because remains preserve very poorly in the hot and humid tropics, and paleontology is underfunded in countries where these apes mostly live.

“This study suggests we have underestimated the number of primate extinctions caused by humans in the past,” says Jo Setchell, a primatologist at Durham University. “Understanding past extinctions will help us to predict how vulnerable current species are, and therefore help us to protect them more effectively,” Setchell adds.

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