Ancient Proteins from Homo erectus Teeth Reveal Genetic Link to Modern Humans

Breakthrough in Ancient Human Genetics

Scientists retrieved proteins from six teeth unearthed in China that reveal a potential link between Homo erectus and later human species, including Homo sapiens. A prehistoric human known as Homo erectus was the first of our forerunners to leave Africa, crossing continents and ultimately roaming the planet for almost 2 million years. But with scarce genetic material available to study, the species remains a major mystery in human origins. Now, scientists have retrieved ancient proteins from six teeth unearthed in China that, for the first time, reveal a molecular link between Homo erectus and later human species, including our own: Homo sapiens.

Novel Extraction Technique

Fu, a professor at the Institute of Vertebrate Paleontology and Paleoanthropology, part of the Chinese Academy of Sciences in Beijing, and her team used what they described as a new, less invasive technique to study fossils without damaging their morphology. Rather than drilling, they used acid etching to remove a small sample of enamel from the teeth.

Evidence of Genetic Contribution

The researchers found that the specimens from the three sites in China shared two amino acid variants, one of which was previously unknown. This finding, the researchers reasoned, suggested the teeth all belonged to the same species. "It suggests that East Asian Homo erectus-related populations may have contributed genetically to Denisovans, and through them indirectly to some modern humans," researchers concluded.

Understanding Human Evolution Networks

From the protein information, the researchers were also able to determine the sex of the fossils — five males and one female — by identifying a sex-specific marker in a tooth enamel gene on the Y chromosome. The finding suggests "a view of human evolution in Asia as a network of populations that sometimes overlapped and interbred, rather than a set of clean, isolated branches."