It all started with a large molar found in an apothecary shop in Hong Kong in 1935. Found amongst a mix of bones and “dragon teeth” as medicine, the tooth palaeontologist Ralph von Koenigswald discovered was definitely not of human origin. At more than twice the size of a human molar, time and testing would later reveal it belonged to a giant ape species from nearly 2 million years ago.
Named Gigantopithecus blacki, the giant ape was a creature to behold: at 3 meters tall (almost 10 feet) and 500 kilograms (1,100 pounds) in weight, the herbivore roamed the Earth up until around 300,000 years ago. The G. blacki fossil record now includes thousands of teeth and four partial mandibles from subtropical Southeast Asia. The team tested a molar found in Chuifeng Cave, China, where 24 large mammalian species have been unearthed, including an ancestor of the giant panda.
"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," said Associate Professor Enrico Cappellini, principal investigator at the University of Copenhagen, to IFLScience.
Published in the journal Nature, the team used a novel technique to rebuild the dental enamel proteins from the fossil remains of this large, forest-dwelling ape. In doing so, the team compared for the first time the results of the protein analysis with a database of hominid proteins in order to place the Gigantopithecus within evolutionary history.
"By sequencing proteins retrieved from dental enamel about 2 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 until now. In this study, we can even conclude that the lineages of orangutan and Gigantopithecus split up about 12 million years ago," said Cappellini.
Previous attempts to place G. blacki could only be made by comparing the shape of the fossils with reference materials from living great apes. Now, the team show that the technology has reached a level of sophistication that makes it possible for ancient enamel proteins to be retrieved from Early Pleistocene samples preserved in subtropical conditions.
"Sequencing protein remains 2 million years old was made possible by stretching to its limits the technology at the base of proteomic discovery: mass spectrometry," said Cappellini. "State-of-the-art mass spectrometers and the top palaeoproteomics expertise needed to get the best out of such sophisticated instrumentation are key resources to achieve this result."
The team say their method holds promise for other ancient remains "to reveal the vast antiquity of human evolution."