Primates, especially gibbons and other monkeys, are rare finds in the Asian fossil record. Fossils from the Pleistocene and Holocene are usually kept in caves, where living gibbons almost never spend time. But humans have preserved the remains of at least one gibbon for posterity by burying it in the tomb of a Chinese noblewoman 2,300 years ago during the Warring States period in China.
The unfortunate monkey was buried with a noblewoman believed to be Lady Xia, the grandmother of Qin Shi Huang, the first Chinese emperor, who reigned from 259 to 210 BCE. Lady Xia also took a leopard, a lynx, an Asiatic black bear, a crane and several pets to her very ornate grave in Chang’an, now Shenheyuan city in Shaanxi province. Morbid menageries are a feature of high-status tombs from this period, but primatologist Samuel Turvey of the Zoological Society of London says archaeologists have never seen a gibbon buried this way.
That in itself is interesting. By the time of Lady Xia, gibbons had become popular among the nobility as pets and symbols of the class of scholars and officials called Junzi. Thanks to the graceful way they swing through the trees, gibbons were considered noble in ancient Chinese culture. So it is culturally important to find a gibbon, believed to be a pet, buried with the grandmother of the first emperor of China. But this particular gibbon, in addition to its proximity to power, may also represent a previously undiscovered – and now extinct – species.
Introduce Junzi Imperialis
“While visiting the archaeological collections in Xi’an, Shaanxi Province, in 2009, I discovered that a half-complete gibbon skull, mandible, and associated skeleton had been discovered in a recently excavated royal tomb from the ancient capital of Chang’an, Turvey told Ars. . “Shaanxi is a huge distance from one of China’s surviving gibbon populations, which immediately suggested that this specimen could be something extremely interesting.”
Turvey and his colleagues measured the distances between certain landmarks on the gibbon’s skull, as well as the shape and proportions of the teeth and bones, and compared them to the four genera of gibbons alive today, comprising a total of 18 species — four of which live in China. Lady Xia’s gibbon didn’t match any of them. “This shows that the Xi’an gibbon is distinct from all living gibbons at a genus level, making it only the eighth known monkey species to have survived the recent historical era,” Turvey told Ars. He and his colleagues named the newly discovered species Junzi Imperialis.
Their analysis gets some extra support from geography. Most of the other animals in Lady Xia’s tomb lived in the southern part of Shaanxi province until recently, meaning the gibbon was probably local as well. Historical records describe that gibbons were not captured near Chang’an . until the 10th centurye century CE, and later records say that wild gibbons lived in Shaanxi province well into the 18th centurye century.
But there are no gibbons in Shaanxi today, and the province is separated from southwest China — home to China’s only remaining gibbons — by several rivers and other major drainages.
“Gibbons are extremely vulnerable to habitat fragmentation, as they are almost entirely confined to the canopy and can rarely cross holes in the forest,” Turvey explains. Rivers often act as physical barriers between gibbon populations, preventing interbreeding, so it’s quite likely that the local gibbon population in Shaanxi was a different species from the gibbons now living in southwestern China.
“In addition to skeletal differences, living gibbons can be distinguished based on different coat color patterns, especially in their facial patterns and by their species-specific songs,” Turvey said. “Unfortunately we don’t know what” Junzic looked or sounded like in life.”
And even with living gibbons, it can be hard to tell species apart just by looking, which is why zoos so often end up hybridizing gibbon species by accident. Genetic testing is the best way to be sure, but Turvey and his colleagues weren’t allowed to do destructive sampling of the remains of Lady Xia’s pet gibbon — and Central China’s subtropical climate usually doesn’t lend itself to good DNA preservation anyway. That leaves us with bones and teeth.
Proclaiming a new species could be a controversial undertaking, and it will take time to see if other primatologists will accept J. imperialis. But the case for J. imperialis was solid enough to pass peer review, and this wouldn’t be the first time a primate species has been accepted based on a single sample.
We may have lost more primates than we realize
Until now, scientists had assumed that no monkey species had become extinct since the end of the last ice age. That assumption is largely based on the fossil record — if we don’t have fossils of primate species that lived during the Holocene and the species doesn’t currently exist, then there’s no reason to believe the species ever existed. And thanks to the wet climate, primate remains aren’t often preserved in the tropics, neither in archaeological sites nor in the recent fossil record — a problem that also frustrated paleoanthropologists studying early human migrations to the region.
But J. imperialis proves that at least one ape species went extinct relatively recently, which may force primatologists and ecologists to reconsider the assumption that humans only began to threaten the very existence of our fellow apes in the last few centuries.
“Until the discovery and description of Junzi Imperialismonkeys and most other primates were thought to have been relatively resilient to past human pressures on biodiversity and the worrying global decline of monkeys was a contemporary phenomenon,” Turvey said. “We now realize that before the The recent historical era may also have been numerous man-made extinctions of apes and other primates.” The absence of extinct primates from the Holocene fossil record may mean that tropical and subtropical climates have obliterated the evidence. We may never know what we’ll find. have already lost.
In fact, there could be multiple now-extinct gibbon species in China, Turvey and his colleagues suggest, as historical records describe gibbons living in central and southern China, also in different areas separated by major rivers of J. imperialis‘ territory near Chang’an and the four gibbon species that inhabit southwestern China today. So far, there’s no direct evidence of other extinct gibbon species, but their discovery would further challenge our assumptions about the amount of primate biodiversity we’ve already lost.
An earlier start of the sixth mass extinction
Should we really blame ourselves for the extinction of? J. imperialis? It’s hard to say for sure, but according to Turley and his colleagues, the most likely culprits are humans.
“Few extinctions in the climate-stable Holocene can even doubtfully be interpreted as non-anthropogenic,” they wrote. And a wave of deforestation near Chang’an late in China’s imperial period is said to have put serious strain on gibbon populations. As previously mentioned, the near inability of gibbons to bridge gaps in the canopy makes them particularly vulnerable to deforestation.
“Tropical deforestation causes gibbon populations to become fragmented and isolated quickly, which can quickly lead to extinction,” Turvey told Ars. And then there’s the fact that gibbons are hunted for food and traditional medicines in much of Asia. In computer models by Turvey and his colleagues, gibbon population decline follows a wavefront of human population expansion — an ecological smoking weapon.
If gibbon species like J. imperialis As early as the 18th century, gibbons may be even more vulnerable to habitat loss and hunting than we thought, which is a sobering thought given the serious threat posed by modern gibbons today. All four species still living in China are critically endangered and only about 26 Hainan gibbons remain, all confined to a single forest area on Hainan Island.
“The discovery of Junzi Imperialis emphasizes the need to focus more conservation efforts on current living gibbon species, especially the four remaining gibbon species in China, which are among the rarest and most endangered mammals in the world,” Turvey said.
Science2018. DOI: 10.1126/science.aao4903 (About DOIs).