400,000-Year-Old H. erectus Teeth Proteins Suggest Denisovan Interbreeding

Researchers have for the first time extracted substantial proteins from 400,000-year-old teeth attributed to Homo erectus, revealing genetic variants that suggest interbreeding between the ancient species and Denisovans in Asia.

A team led by Qiaomei Fu at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing analyzed dental enamel from six teeth recovered at three sites in China: one from Zhoukoudian, two from Hexian and three from Sunjiadong. Using a protein called amelogenin Y to determine sex, the researchers identified five males and one female. The analysis yielded 11 proteins and hundreds of amino acid positions, including two notable variants in all samples.

One variant has not appeared in any known human lineage, potentially marking a unique trait of East Asian H. erectus populations. The other matches a variant found in Denisovans, archaic humans who lived in Asia until around 30,000 years ago. Denisovan genomes contain DNA from an unknown hominin, and the team proposes that H. erectus contributed this variant through interbreeding. This signal later passed to some modern humans via Denisovan-Homo sapiens mating tens of thousands of years ago.