The extinction of the giant ape: a long-standing mystery solved

Giants once roamed the karst plains of southern China, apes measuring three meters and weighing 250 kilograms. These very distant human ancestors – Gigantopithcus blacki – disappeared before humans arrived in the region, with few clues as to why, and leaving so far around 2,000 fossilized teeth and four jaws as the only signs of their existence.

New evidence from this region published in Naturediscovered by a team of Chinese, Australian and American researchers, demonstrates beyond doubt that the largest primate to have walked on Earth disappeared between 295,000 and 215,000 years ago, unable to adapt its food preferences and behaviors, and vulnerable to climate change that has sealed it’s destiny.

“The story of G. blacki is an enigma in paleontology: how could such a powerful creature disappear at a time when other primates were adapting and surviving? The unresolved cause of its disappearance has become Holy Grail in this discipline,” explains the paleontologist. and co-senior author Professor Yingqi Zhang from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (IVPP).

“The IVPP has been searching for evidence of G. blacki in this region for over 10 years, but without solid dating or consistent environmental analysis, the cause of its extinction had eluded us.”

The definitive evidence revealing the story of the giant ape’s extinction comes from a large-scale project collecting evidence from 22 cave sites spread across a vast region in southern China’s Guangxi province. The basis of this study was dating.

“It is a major feat to present a defined cause for the extinction of a species, but establishing the exact time a species disappears from the fossil record gives us a target timeline for environmental reconstruction and behavioral assessment ” says co-lead author Kira Westaway, Macquarie University geochronologist, associate professor.

“Without solid dating, you’re just looking for clues in the wrong places.”

Six Australian universities contributed to the project. Macquarie University, Southern Cross University, University of Wollongong and the University of Queensland used several techniques to date the samples. Southern Cross also mapped the teeth of G. blacki to extract information about the monkeys’ behaviors. The ANU and Flinders University studied pollen and fossil sediments from the cave, respectively, to reconstruct the environments in which G. blacki flourished and then disappeared.

Six different dating techniques were applied to the cave sediments and fossils, producing 157 radiometric ages. These were combined with eight sources of environmental and behavioral evidence and applied to 11 caves containing evidence of G. blacki, as well as 11 caves of a similar age range in which no evidence of G. blacki n was found.

Luminescence dating, which measures a light-sensitive signal found in burial sediments that enclosed G. blacki fossils, was the primary technique, supported by serial uranium (US) and spin resonance dating. electronic (US-ESR) of the G. the black teeth themselves.

“By directly dating the fossil remains, we confirmed that their age matches the sequence of luminescence in the sediments where they were found, giving us a complete and reliable timeline of the extinction of G. blacki,” explains the geochronologist from Southern Cross University, Associate Professor Renaud. Joannès-Boyau.

Using detailed pollen analysis, faunal reconstructions, stable isotope analysis of teeth, and detailed micro-level analysis of cave sediments, the team established the environmental conditions that led to the extinction of G blacki. Then, using textural analysis of trace elements and dental microwear (DMTA) of the monkeys’ teeth, the team modeled the behavior of G. blacki while it was thriving, compared to that when it disappeared. ‘species.

“The teeth provide a stunning insight into the behavior of the species, indicating stress, diversity of food sources and repeated behaviors,” says Associate Professor Joannes-Boyau.

The results show that G.blacki became extinct between 295,000 and 215,000 years ago, much earlier than previously thought. Before this time, G. blacki thrived in a rich and diverse forest.

Between 700,000 and 600,000 years ago, the environment became more variable due to the increased strength of the seasons, causing a change in the structure of forest communities.

Orangutans (genus Pongo), a close relative of G. blacki, adapted their size, behavior, and habitat preferences as conditions changed. In comparison, G. blacki relied on a less nutritious backup food source when its preferences were not available, decreasing its food diversity. The monkey became less mobile, had a reduced geographic range in which to feed, and faced chronic stress and a decline in numbers.

“G. blacki was the ultimate specialist, compared to more agile adapters like orangutans, and this ultimately led to its demise,” says Professor Zhang.

Associate Professor Westaway said: “With the threat of a sixth mass extinction looming, there is an urgent need to understand why species are disappearing.

“Exploring the reasons for unresolved past extinctions gives us a good starting point for understanding the resilience of primates and the fate of other large animals, in the past and in the future.”