Chinese scientists have achieved a major breakthrough in paleoanthropology by obtaining molecular information from teeth of 400,000-year-old Homo erectus for the first time, offering new evidence about the evolutionary relationship between ancient humans and modern populations.

The study, conducted by researchers at the Institute of Vertebrate Paleontology and Paleoanthropology under the Chinese Academy of Sciences, was published on Wednesday in the journal Nature.

Researchers said the findings reveal that Homo erectus populations represented by the Peking Man site in Zhoukoudian, Beijing, the Hexian site in east China's Anhui Province, and the Sunjiadong site in central China's Henan Province belonged to the same evolutionary population.

The study also uncovered evidence suggesting that genetic material from Homo erectus may have indirectly entered modern human populations through the Denisovans, helping address a long-standing question in human evolution over whether Homo erectus had any genetic connection to modern humans.

Homo erectus was among the earliest human ancestors to migrate out of Africa and spread across Eurasia and Southeast Asia, occupying a crucial place in human evolutionary history. However, due to the difficulty of preserving ancient DNA, its genetic characteristics have remained largely unknown.

The Chinese research team analyzed six Homo erectus tooth fossils dating back around 400,000 years from the Zhoukoudian, Hexian and Sunjiadong sites, along with one ancient human tooth fossil from Harbin used as a reference sample.

To preserve the integrity of the fossils, researchers first conducted non-destructive screening of ancient proteins in the samples. They then used a minimally invasive acid-etching technique to extract tiny amounts of material from the enamel surface.

Using three specialized software systems for cross-verification, the team successfully identified multiple endogenous enamel proteins and obtained extensive peptide and amino acid site information.

Researchers said this marks the first time that characteristic molecular data from Homo erectus has been recovered globally. The achievement also pushes back the time limit of proteomic research on ancient humans in East Asia from about 160,000 years ago to at least 400,000 years ago.

The team also developed a new method for identifying the sex of ancient human fossils based on protein characteristics. The technique can accurately determine the sex of tooth fossils and provides a reliable new tool for studying ancient human remains that lack clear morphological features or preserved DNA.