The teeth of a giant ape that was twice as tall as an adult human have been discovered in southern Chile.
The extinct ape, dubbed Gigantopithecus blacki, roamed the Earth around 2 million years ago, and is believed to be related to living orang-utans.
The researchers say the genetic materials, which were retrieved from the molar fossil by breaking down their proteins, are "the oldest known skeletal proteins sequenced to date".
They add that the findings, published in the journal Nature, show the possibility of extending "the evolutionary relationships between modern humans and extinct ones further back in time, at least up to two million years".
The oldest human fossil remains with conserved DNA date back 400,000 years – leaving a void in evolutionary history.
Frido Welker, a postdoctoral researcher at the Globe Institute, University of Copenhagen, and first author of the study, said: "Primates are relatively close to humans, evolutionary speaking."
He added: "This means that we can potentially retrieve similar information on the evolutionary line leading to humans."
The researchers used a technique known as mass spectrometry to sequence the dental enamel proteins of the Gigantopithecus.
The process involves breaking down proteins into peptides – which are short chains of amino acids – and analysing their masses to figure out their chemical composition.
This technique was also recently used to extract genetic information from a 1.7-million-year-old rhino tooth.
The method has been hailed as a "game changer" by scientists as it is able to acquire genetic information – especially from fossils excavated from subtropical regions – that were previously unobtainable using DNA testing.
Dr Welker said: "Until now, it has only been possible to retrieve genetic information from up to 10,000-year-old fossils in warm, humid areas."
The fossil remains of the Gigantopithecus – comprising a few lower jaws and lots of teeth – were initially discovered in 1935 in Chuifeng Cave in southern China but due to lack of cranial remains, scientists were unable to reconstruct the physical appearance of this mysterious animal.
Protein sequencing allowed the researchers to paint a picture of what the Gigantopithecus, which became extinct around 300,000 years ago, may have looked like.
They believe the giant primate was around three metres tall and weighed around 600kg.
The proteins from the sample suggest that the dental enamel may have belonged to a female.
Enrico Cappellini, an associate professor at the Globe Institute and senior author on the study, said: "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."
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