The largest known primate went extinct between 295,000 and 215,000 years ago, probably driven by its inability to adapt its food preferences amid a changing climate.
A relative of today’s orangutans, Gigantopithecus blacki, known as “Giganto”, was 3 metres tall and weighed up to 300 kilograms.
Despite surviving for more than 2 million years, the species has been a bit of an enigma since its fossilised tooth was found in a traditional medicine shop in Hong Kong in 1935. The enormous tooth was initially purported to belong to a dragon, but palaeontologists quickly recognised it was, in fact, from a primate.
“When you think about them, you think about giants,” says Kira Westaway from Macquarie University in Sydney, Australia. “Normally when you think about a giant, you think about a dinosaur, but this was a giant in the primate family.”
To establish a timeline for when the ape went extinct, Westaway and her colleagues studied hundreds of its teeth and four jawbone fragments found in caves across Guangxi province in southern China. Looking at the radioactive decay of certain elements, such as uranium, within teeth and bone allows researchers to gauge how much time has passed since death.
They also looked at other deposits, such as pollen and sediment, within the caves to determine the conditions that G. blacki – a herbivore – lived in.
“We show that, from 2.3 million years ago, the environment was a mosaic of forests and grasses, providing ideal conditions for thriving G. blacki populations,” the researchers write. “However, just before and during the extinction window between 295,000 and 215,000 years ago, there was enhanced environmental variability from increased seasonality, which caused changes in plant communities and an increase in open forest environments,” they add.
By studying banding in the animals’ fossilised teeth, the researchers detected signs of chronic stress caused by a lack of availability of their favourite food. Being unable to adapt to a shifting climate, and the food variability that came with it, probably sealed the creature’s fate, they say. In contrast, orangutans, of which there are three surviving species, adapted their dietary preferences and behaviour in response to increasing climate variability.
“Ultimately [G.blacki’s] struggle to adapt led to the extinction of the greatest primate to ever inhabit the Earth,” the researchers write. They also dispel the idea that hominins may have competed with or hunted the species, helping to drive its demise. “There is no evidence for this,” says Westaway.
Julien Louys at Griffith University in Queensland, Australia, says the researchers present a convincing case that changing environments, and particularly increased habitat variability, probably had detrimental effects on G. blacki.
He adds, however, that the fossils studied came from a quite restricted geographical region. Fossils resembling G. blacki have also been found in Thailand, Vietnam and Indonesia.
“One thing seems almost certain: their actual geographical range through time would have been much greater than current fossils indicate,” says Louys. “How much this will affect the timing of the global extinction of the species is impossible to tell.”
Anne-Marie Bacon at the French National Centre for Scientific Research says that the study helps us to understand G. blacki’s extinction, but just studying fossils from China only reveals part of its history.
“This paper focuses on Chinese records, but due to the scarcity of palaeontological sites in Asia, we don’t know if the geographical range of the giant ape extended on the Indochinese peninsula [mainland South-East Asia], and, furthermore, what was the southernmost limit of this range,” she says.