Dragon teeth ‘reveals the place of the ancient monkey in the primate family tree

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In 1935, the anthropologist Gustav von Koenigswald encountered several strange teeth in drug stores in Hong Kong and South China. Samples sold as “dragon teeth” ground for use in Chinese medicine were special: Apelike, but they were huge – molars of other fossils or living primates were much larger. Its dimensions (and four fossilized jaw bones) suggested that Gigantopithecus blacki was the largest primate ever discovered and was about 3 meters high. But without any skulls or skeletons, the researchers did not know whether the animal that lived about 2 million to 200,000 years ago is a relative of today’s orangutans, today’s African monkeys, or something else entirely.

Now, by combining clues from proteins in the enamel of a 1.9-million-year-old tooth found in Chuifeng Cave in southern China, researchers have evidence that they eventually let G. place blacki in the primate family tree. The study solves a long-running evolutionary puzzle and shows that genetic information can survive in proteins in much longer and more difficult conditions than many people think.

Frido Welker and colleagues, an evolutionary geneticist at the University of Copenhagen, began to examine G. blacki teeth for robust protein fragments called peptides that could be preserved for much longer than fragile DNA, which could be preserved for up to several million years. Welker and his colleagues dissolved small amounts of enamel from G. blacki mo and used mass spectrometry to identify more than 500 peptides that fit six proteins. They compared amino acids, orangutans, gorillas, and other monkeys and monkeys to those found in the same six proteins in living monkeys, and calculated that the giant monkey was most closely related to orangutans. The two lines probably left 10 million to 12 million years ago, today they report in Nature.

This is not completely unexpected, says paleoanthropologist Russell Ciochon of the University of Iowa in Iowa City was not involved in the study. But having direct molecular evidence – especially the timing of division – is exciting. The study also shows for the first time that fossil teeth can hold genetic information that can be used for millions of years in hot and humid areas where organic matter breaks down faster. Although the tooth itself is just shy of 2 million years, the cave’s warm temperatures (average 20 ° C) push the “thermal age” to 12 million years – skeletal proteins that have been sequenced to about five times the thermal age of others. “We now know that we can get [genetic information] from something almost 2 million years old from a subtropical environment,

The key is to focus on enamel proteins, he said. Both before and after death, minerals in tooth enamel keep water out and help the tooth resist decomposition. The success with G. blacki suggests that enamel from other fossil teeth may help sort out the relationships between other early apes, Ciochon also includes how G. blacki relates to the great apes living in India and Pakistan. And because 12 million years of human fossils are close to the thermal age of many interesting fossils, Cappellini said, “This brings us closer to thinking that it is possible to investigate hominins from Africa. At least it’s possible. “


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