The greatest monkey that ever lived was not too big to fail
Gigantopithecus blacki, almost the size of a basketball hoop and as heavy as a grizzly bear, was the largest ape that ever lived. During the Pleistocene, Gigantopithecus roamed southern China for more than a million years. But by the time ancient humans reached the region, Gigantopithecus was gone.
To determine why these miraculous primates became extinct, a team of scientists recently analyzed clues preserved in Gigantopithecus teeth and cave sediment. Their findings were published in the journal on Wednesday Naturereveal that these nearly 10-foot-tall monkeys were most likely doomed by their specialized diet and inability to adapt to a changing environment.
Paleontologists first discovered Gigantopithecus in the mid-1930s in a pharmacy in Hong Kong, where the monkey’s unusually large molars were promoted as “dragon’s teeth.” The animal is named in honor of Davidson Black, the Canadian scientist who studied the early human ancestor known as Peking Man. In the decades since, scientists have unearthed about 2,000 Gigantopithecus teeth and a handful of fossil jawbones from caves throughout southern China.
The lack of fossilized bones makes the reconstruction of Gigantopithecus difficult; paleoartists depict the ancient ape as an orangutan (its closest living relative) crossed with a silverback gorilla, only larger. Nevertheless, the great ape’s teeth, which are encased in a thick layer of enamel, contain a wealth of clues about how these enigmatic primates lived and possibly why they went extinct.
Yingqi Zhang, a paleontologist from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and author of the new paper, has studied the fossils of Gigantopithecus for more than a decade. To determine what drove them to extinction, Dr. Zhang pinpoint exactly when Gigantopithecus disappeared. He worked with Kira Westaway, a geochronologist at Macquarie University in Australia.
“To pinpoint exactly when Gigantopithecus disappears from the fossil record requires accurate dating – otherwise you’re looking in the wrong places for clues to its extinction,” said Dr. Westaway.
The team collected and dated material from 22 caves in southern China. To refine the age of the fossils and cave sediments, the researchers applied six dating techniques. They also analyzed isotopes and pollen in the samples to simulate what the region’s environment looked like around the time Gigantopithecus disappeared. Finally, they compared wear patterns in the oversized teeth with fossilized teeth from Pongo weidenreichi, an extinct orangutan that lived alongside Gigantopithecus.
Gigantopithecus, they say, went extinct between 295,000 and 215,000 years ago. These dates were much more recent than previous estimates and coincide with a dynamic period of environmental change.
The pollen samples showed that before that extinction window, the local environment was dominated by evergreen trees that created closed-canopy forests. Gigantopithecus seemed well suited to those environments. Analysis of isotopes in Gigantopithecus teeth from that period revealed that the monkeys ate fibrous plants, fruits and flowers.
About 600,000 years ago, the region’s climate began to change with the seasons, as dense forests gave way to a patchwork of open forests and grasslands. That led to “dry spells where fruit was hard to find,” said Dr. Westaway. Unlike ancient orangutans, which adapted by eating a varied diet of shoots, nuts, seeds and even insects, Gigantopithecus switched to less nutritious alternatives such as bark and twigs. Their teeth from this period show signs of chronic stress.
As the environment became unfavorable, Gigantopithecus’ size began to work against this. Unlike feisty orangutans, which could travel greater distances through the canopy and into open environments to forage, the ground-bound Gigantopithecus were most likely restricted to shrinking patches of forest.
According to Sergio Almécija, a paleoanthropologist at the American Museum of Natural History who was not involved in the new research, the demise of Gigantopithecus reveals that even the largest animals are vulnerable to becoming too specialized.
“These monkeys became so specialized in living in a specific environment that as soon as that environment changes, they disappear,” he said.
Modern orangutans face a fate similar to that of their giant relatives. While their ancestors were able to adapt to a changing environment, these tree specialists are threatened by deforestation. “Their forests are getting smaller and smaller and every year we have fewer and fewer orangutans,” said Dr. Almecija.