A research group successful retrieved genetic materials from a 1.9-million-year-old Gigantopithecus blacki fossil for the first time, confirming the close evolutionary relationship between this extinct species and the extant Asian orangutan. This project was led by Wei Wang, a professor from the Institute of Cultural Heritage at Shandong University and Prof. Enrico Cappellini of the University of Copenhagen. It was the first time to extract such an ancient protein from a fossil from a subtropical environment. The article, "Enamel Proteome Shows that Gigantopithecus was an Early Diverging Pongine", was published in the journal Natureon November 14, 2019.

Gigantopithecus was the largest primate that had ever lived on Earth. Fossil evidence indicates that they were widespread in south China, such as Guangxi, Hainan, Guizhou, Chongqin, and Hubei. To date, 17 fossil sites have been found and 13 of them in southwest Guangxi.Gigantopithecus appeared 2 million years ago and went extinct approximately 300,000 years ago. According to their huge teeth and mandibles, which are double to triple that of a human's, paleoanthropologists presume their height to be more than 2 meters and weigh over 300 kg.

In 1935, the Dutch paleontologist von Koenigswald first discovered the fossils of the giant ape from a Chinese drug store in Hong Kong. He identified three big teeth of an unknown primate and proposed the name ofGigantopithecus blacki. By the 1950s to 1960s, Chinese paleontologists had found the precise homeland ofGigantopithecusin Guangxi. In the last 20 years, many fossil locations of various ages have been discovered in the caves of the Baise Basin and Chongzuo region, Guangxi. Chinese paleoanthropologists have clarified the time of emergence and extinction of this giant ape.

However, the origin and evolution of Gigantopithecus have puzzled the academic community for a long time, such as its evolutionary relationship to other fossil great apes of the late Miocene era and the extant orangutan.

The proteome was extracted from a broken molar of the Gigantopithecus, which was excavated at the Chuifeng Cave site in 2008. The cave is about 77 meters above ground level, 19 meters in length, 0.5-2 meters in width, and 1.5-5 meters in height. The excavation, conducted by Prof. Wang in 2008, yielded a discovery of rich mammal fossils, including 93 teeth of the Gigantopithecus, the associated Stegodon preorientalis, the Ailuropoda microta, the Equus yunnanensis and species that are typical fauna of the early Pleistocene. Further ESR combined U-aeries dating indicates that the age of Chuifeng fauna is 1.93 million years before the present.

"A long-unresolved issue comes to a solution," said paleoanthropologist and study co-author Wei Wang of Shandong University in China. "Its origin and evolution have puzzled paleoanthropologists for more than half a century."

It marked the first time that genetic material this old has been recovered from a fossil found in a warm, humid environment - conditions usually inhospitable to such preservation. The researchers expressed hope that the same technique could be applied to other fossils, perhaps including species in the human evolutionary lineage.

Wang said the Gigantopithecus may have had an orangutan-like appearance and most likely was a ground-dweller, unlike orangutans, who spend most of their time in trees. It likely relied on a plant-based diet, perhaps eating sweet foods like fruit in forested environments, judging from the cavities seen in its teeth, Wang said.

"Primates are relatively close to humans, evolutionary speaking. With this study, we show that we can use protein sequencing to retrieve ancient genetic information from primates living in subtropical areas even when the fossil is two million years old. Until now, it has only been possible to retrieve genetic information from up to 10,000-year-old fossils in warm, humid areas. This is interesting, because ancient remains of the supposed ancestors of our species, Homo sapiens, are also mainly found in subtropical areas, particularly for the early part of human evolution. This means that we can potentially retrieve similar information on the evolutionary line leading to humans", says Frido Welker.

"By sequencing proteins retrieved from dental enamel about two million years old, we showed it is possible to confidently reconstruct the evolutionary relationships of animal species that went extinct too far away in time for their DNA to survive till now. In this study, we can even conclude that the lineages of orangutan and Gigantopithecus split up about 12 million years ago", says Enrico Cappellini.

Source: the Institute of Cultural Heritage at Shandong University

Written by: Liao Wei

Edited by: Matthew Lane, Xie Tingting