A protein variant in ancient Homo erectus teeth is carried by 21% of people in the Philippines today

A protein variant found in 400,000-year-old Homo erectus teeth from China turns up in living people at a frequency of 21% in the Philippines and about 1% in India. The variant sits in ameloblastin, a protein involved in building tooth enamel, and it had previously been seen in Denisovans. Researchers read the pattern as a trace of Homo erectus ancestry that passed through Denisovans into some modern populations.

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No DNA was needed to draw the link, because none usable survived in the fossils.

The work is a Nature paper called “Enamel proteins from six Homo erectus specimens across China,” led by Qiaomei Fu of the Chinese Academy of Sciences and published online on May 13, 2026. The Philippine and Indian figures reached a wider audience when ScienceDaily republished a Conversation article by Sally Christine Reynolds, a hominin palaeoecologist at Bournemouth University, in early November. Reynolds is not an author of the study, so her reading of the results is an outside expert’s summary and not the authors’ own wording.

Six teeth from Zhoukoudian, Hexian and Sunjiadong

The team analyzed enamel from six teeth belonging to six individuals, five male and one female by the Nature Asia press summary, all dated to about 400,000 years ago. They came from three Chinese sites: Zhoukoudian outside Beijing, Hexian in Anhui province and Sunjiadong in Henan province, as Sci.News lists them. Enamel is the hardest tissue in the body and shelters proteins long after DNA has broken down, which is why the approach reaches back further than genome sequencing can.

One result is about identity. All six specimens share an amino acid change never recorded in any other hominin, which groups the East Asian fossils into a distinct cluster. The Leakey Foundation’s summary says this helps settle a long debate over whether the unusual Hexian fossils belong to Homo erectus at all.

Recovering proteins rather than DNA is the technical story underneath. Warm, wet climates wreck DNA within tens of thousands of years, but amino acid sequences from enamel can still be read by mass spectrometry. Each sequence gives a short list of positions where a species or population differs, and the six teeth gave the team a comparison set that did not exist before this work.

Zhoukoudian is the cave complex long associated with the fossils once called Peking Man, so the new proteins tie a famous site to a molecular record for the first time in this form. The other two sites have been less visible in public accounts, which gives the set a mix of well-known and lesser-known material from northern and central China, spread across hundreds of kilometers.

AMBN-A253G and the Denisovan variant AMBN-M273V

Two variants appear in all six teeth. The first, AMBN-A253G, is new to science and may serve as a marker for East Asian Homo erectus. The second, AMBN-M273V, is the one that links to living people. Sci.News reports it had been found before only in Denisovans, and the Leakey Foundation puts its frequency at about 21% in the Philippines and about 1% in India.

The authors propose that Homo erectus populations passed AMBN-M273V to Denisovans through interbreeding and that Denisovans later handed it to the ancestors of Southeast Asians and Oceanians. The 21% figure sits comfortably with that route, since Denisovan ancestry is known to be strongest in parts of Southeast Asia and Oceania.

The contrast between the two countries is worth reading closely. A frequency of 21% in the Philippines against about 1% in India fits the pattern geneticists have found for Denisovan DNA, which is richest in island Southeast Asia and Oceania and thin in South Asia. A protein variant that follows the same map is a second line of evidence pointing the same way.

Interbreeding as a routine event

Reynolds drew the broad conclusion in her article: interbreeding between archaic human lineages was not exceptional and was routine. She wrote that as an interpretation of the pattern across lineages, not as a measurement from these six teeth, and the paper’s own claim is narrower, namely that the two populations may have coexisted and interacted in parts of East Asia.

Protein evidence has limits that DNA does not. A single amino acid change records one position, whereas a genome records millions, so a shared variant is consistent with interbreeding but could in principle arise by other routes, such as parallel change or retention of an older version. The authors weigh the interbreeding route as the most likely, and the broader community will decide how far to push it.

The authors call for more molecular data from Homo erectus specimens of other periods and regions before the picture is firmed up. Six individuals from three sites is a small sample, and protein data cannot show how the variant moved between populations, only that it was present in one and later in the other.

The biggest unanswered question is what the variant does. The Leakey Foundation notes that the functional effects of the Homo erectus-derived variant are unknown, so for now the 21% figure in the Philippines marks a lineage signal rather than a trait with any known consequence for health or appearance.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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