Scientists Say They Know What Killed Off Giganto

The largest primate to ever live roamed southeastern Asia for more than a million years—but left behind plenty of mystery. Despite 85 years of searching, the fossil record for Gigantopithecus blacki—or giganto—is made up of just four jawbones and 2,000 teeth, and scientists didn't know exactly what caused it to die out. Now they think they do, and it involves climate change and fruit. The creature stood 10 feet tall, weighed up to 650 pounds, and survived for around 2 million years on the forested plains of China's Guangxi region. It ate a vegetarian diet, munching on fruits and flowers in tropical forests, until the environment began to change.

The Guardian reports the key was determining exactly when the species died out. As co-author Dr. Kira Westaway of Macquarie University explains, "If you don't have an accurate timeline, then you're just looking for clues in the wrong places. It was assumed that the deterioration in forests was the cause of its demise as it couldn't live in open grasslands—but our study shows that this [shift to savannah] occurred at about 200,000 [years ago] when G. blacki was already extinct," she says.

The team relied on a range of techniques to date giganto teeth and sediment from 11 Guangxi caves; sediment from another 11 caves where no giganto fossils were found was also tested. They found the giant apes didn't vanish quickly, but likely went extinct between 215,000 and 295,000 years ago. They also found forests produced fewer fruits starting around 600,000 years ago, as the region experienced more dry seasons. While smaller apes may have been able to climb trees to search for different food, the researchers' analysis shows the giant apes ate more tree bark, reeds, and other non-nutritious food, reports the AP.

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"It's just a massive animal—just really, really big," said Renaud Joannes-Boyau, a researcher at Australia's Southern Cross University and co-author of the study published in the journal Nature. "When food starts to be scarce, it's so big it can't climb trees to explore new food sources." Per the study, "Ultimately its struggle to adapt led to the extinction of the greatest primate to ever inhabit the Earth." (More discoveries stories.)