Mysterious giants once roamed the forests of Southeast Asia: With an estimated body weight of 250 kilograms, Gigantopithecus is considered the largest primate of all time. A study now sheds light on the question of when and why these great apes became extinct. According to new tooth dating, the end came between 295,000 and 215,000 years ago. Further research results indicate that Gigantopithecus was unable to adapt to the environmental changes that occurred as a result of climatic changes in its habitat.
The history of research into Gigantopithecus began with a curious find from 1935: in a collection of orangutan teeth from a traditional Chinese pharmacy, the German-Dutch paleontologist Gustav Heinrich Ralph von Koenigswald discovered an astonishingly large molar. He assigned it to an apparently huge great ape: Gigantopithecus blacki entered the stage of paleontology for the first time. Around 2,000 additional fossil teeth and four jawbones have now been discovered that are attributed to this former representative of the great apes. The finds come primarily from the south of China. It is estimated that Gigantopithecus could have been three meters tall when erect and weighed 250 kilograms or more.
In an earlier study, researchers were able to prove that Gigantopithecus was related to orangutans using proteins from a tooth that was around two million years old. Both therefore probably went back to a common ancestor who lived ten to twelve million years ago. Gigantopithecus also shared its habitat with a representative of the orangutans, as evidenced by finds. But unlike its smaller relative, the giant disappeared over the last few millennia. However, exactly when and why they died out remained unclear. “The history of Gigantopithecus has been a paleontological mystery,” says co-first author Yingqi Zhang from the Chinese Academy of Sciences in Beijing.
On the trail of extinction
The new evidence that Zhang and his international colleagues are now presenting is based on the results of examinations of fossils and sediments from a total of 22 caves in southern China. The study was initially based on dating from which the time window for the extinction of Gigantopithecus could be derived. Various dating techniques were used. The most important results came from luminescence dating of the sediments in which the fossils were found and the age determination of the Gigantopithecus teeth using two modern dating methods. “By directly dating the fossils, we confirmed that their age matches the luminescence sequence in the sediments in which they were found,” says senior author Renaud Joannes-Boyau of the Chinese Academy of Sciences.
As the team reports, the dating results of the fossils showed that Gigantopithecus became extinct between 295,000 and 215,000 years ago. “Determining when a species disappears from the fossil record provides clues for environmental reconstruction and further assessments,” says co-first author Kira Westaway from Macquarie University in Sydney, Australia. The researchers examined the characteristics of the habitat of Gigantopithecus using plant pollen and fossils of other living beings in the sediments before and during the period of extinction. They also looked for features of the animals' dental material for evidence of changes in their lifestyle over the course of their existence - from the heyday to the decline. The team compared the results with analysis results of teeth from the orangutan species, which existed parallel to Gigantopithecus. “Teeth provide insights into the behavior of a species and indicate, among other things, stress and the diversity of food sources,” says Joannes-Boyau.
A lack of adaptability led to the end
As the team reports, the environmental reconstruction combined with dental analysis and dating results revealed that when Gigantopithecus was well, its habitat consisted of lush forests. There, the giant monkeys were apparently able to eat a wide range of vegetation and fruits - with little seasonal fluctuation. But before and during the extinction window, there were clear changes in the findings: the climate changed and there were seasonal fluctuations.
Apparently this was an unfavorable development for Gigantopithecus. The results of the dental analyzes reflected that his diet became less varied and he drank less water. Certain structural changes in the dental structures of animals of this era also indicate increased stress, the researchers report. The orangutans of this time, however, coped better with the changes, according to the findings. It is possible that their ability to climb enabled them to use more food sources than their giant relatives who only lived on the ground, the researchers write. “Gigantopithecus was probably a specialist compared to the more adaptable orangutans, and this led to its downfall,” Zhang summarizes.
Westaway also sees current significance in the results in light of global changes and species extinction: “Researching the reasons for extinctions can give us clues about how resilient primates and other animals have been in the past and could be in the future,” says the Scientist concludes.
Source: Macquarie University, specialist article: Nature, doi: 10.1038/s41586-023-06900-0