What Caused the Mysterious Extinction of ‘Giganto,’ the World’s Largest Ape?

Standing nearly ten feet tall and weighing up to 660 pounds, the largest great apes to ever live—called Gigantopithecus blacki—roamed modern-day China for nearly two million years. But despite their lengthy existence and decades of searching by paleontologists, the complete fossil record of the animals consists of a mere four jawbones and roughly 2,000 isolated teeth.

The species, dubbed “Giganto,” has long puzzled scientists—and during the Pleistocene epoch, it mysteriously went extinct.

Now, researchers say prehistoric climate changes may have led to the species’ downfall, according to a paper published Wednesday in the journal Nature. The huge apes, it seems, couldn’t adjust their diets to keep pace with the shifting environment.

“It’s just a massive animal—just really, really big,” study co-author Renaud Joannes-Boyau, a researcher at Australia’s Southern Cross University, tells Christina Larson of the Associated Press. “When food starts to be scarce, it’s so big it can’t climb trees to explore new food sources.”

While the apes likely resembled their smaller, modern orangutan relatives, they were pickier eaters than the primates of today. They likely enjoyed the soft fruits and flowers of their tropical habitat, but if these were not available, the apes may have turned to tree parts with low nutritional value, the researchers report.

To reach this conclusion, scientists examined some of Giganto’s remains that had been unearthed in southern China caves between the Yangtze River and the South China Sea. They utilized a full toolkit of techniques to date preserved teeth and sediment from the caves, which narrowed down the primates’ extinction window to roughly 215,000 to 295,000 years ago.

Next, researchers analyzed pollen and sediments near sites of the fossil discoveries and found indications that an environmental shift occurred around that time, as more extreme wet and dry seasons led formerly dense forests to become interspersed with grassy areas.

“The forest cover is still pretty high when Giganto goes extinct, so it wasn’t just a deterioration of the forest,” says study co-author Kira Westaway, a geochronologist at Macquarie University in Australia, to Scientific American’s Meghan Bartels. “It was more Giganto’s response to this changing plant community.”

While other ape species in the area adjusted their diets and behavior, Giganto seemed steadfast, remaining on the ground rather than climbing to reach meals. The team examined banding patterns in the apes’ teeth and discovered signs of chronic stress, since they could no longer eat their preferred fruits.

“During the period of extinction, we see a lot more scratches and pits on the teeth, showing that it was eating more fibrous foods like bark and twigs,” Westaway says to Scientific American.

Hervé Bocherens, a biogeologist at the University of Tubingen in Germany, has conducted research on Giganto’s teeth, which also suggested the giant apes’ lack of a flexible diet played a role in their extinction.

“Our previous work did not benefit from the same robust chronological framework as this new paper, so we could not develop a scenario as detailed as the authors did,” Bocherens, who was not involved in the new research, tells the Guardian.

Other scientists caution that the new study might not provide Giganto’s full story. Though the team’s evidence is convincing, they did not consider possible fossils of the species found in Thailand, Vietnam or Indonesia, paleontologist Julien Louys of Australia’s Griffith University tells New Scientist’s James Woodford.

“One thing seems almost certain: Their actual geographical range through time would have been much greater than current fossils indicate,” he tells the publication. “How much this will affect the timing of the global extinction of the species is impossible to tell.”

Ultimately, by building robust insight into Giganto’s habitat, behavior and timeline, the researchers hope to provide insight into extinction events of today, Westaway tells the Guardian, especially as human activity potentially pushes Earth into a sixth mass extinction.

Ella Weaver | READ MORE

Ella Weaver is a reporter based in Chicago. She has previously written for Popular Science, and her science coverage typically focuses on emerging technologies and sustainability studies.