A study published in Nature has extracted ancient proteins from 400,000-year-old Homo erectus teeth, indicating that the species may have exchanged genes with Denisovans in East Asia and may have left a small but detectable genetic trace in living people in the Philippines, Papua New Guinea and across Southeast Asia.
The research by Qiaomei Fu of the Chinese Academy of Sciences and colleagues analysed tooth enamel from six specimens collected at the Zhoukoudian, Hexian and Sunjiadong sites in China. Tooth enamel is the hardest tissue in the body, and its proteins survive long after DNA has degraded beyond recovery. The team recovered amino acid sequences that carried a previously unknown variant, unique to these east Asian Homo erectus specimens, confirming their identity and settling a debate about whether the Hexian fossils belonged to the species.
A second protein variant was shared with Denisovans, a mysterious archaic human group known primarily from a cave in Siberia. The corresponding genetic variant appears in modern humans at frequencies of 21 percent in the Philippines and roughly 1 percent in India, distributed in a pattern consistent with inheritance through Denisovan ancestry. The most reasonable interpretation is that Homo erectus populations passed this variant to Denisovans through interbreeding, and Denisovans later passed it to the ancestors of modern Southeast Asians and Oceanians.
The findings add to a growing body of evidence that the traditional model of human evolution, a single African origin followed by complete replacement of all other hominins, is incorrect. Instead, interbreeding between archaic human lineages appears to have been routine. Modern humans outside Africa carry roughly 2 percent Neanderthal DNA; Papuans and Aboriginal Australians carry an additional 2–5 percent Denisovan ancestry. The new study adds further weight to the view that even Denisovans themselves received gene flow from something older and more diverged, likely Homo erectus.
The implications extend beyond the specific variants. The study demonstrates that proteomics can recover meaningful biological information from fossils far too old for DNA analysis. The same approach could be applied to other ancient hominins, such as Homo floresiensis and Homo luzonensis, whose genetic contributions, if any, remain unknown. Our genomes are not the product of a single unbroken lineage but mosaics assembled from multiple archaic groups, each adapted to its own environment.
Analysis
Why This Matters
- Shows that Homo erectus was not an evolutionary dead end but contributed to modern human genomes through interbreeding with Denisovans.
- Demonstrates that interbreeding between archaic human lineages was routine, meaning our genomes are mosaics of contributions from multiple ancestral groups.
- Opens a new avenue for studying ancient hominins that cannot be analysed through DNA, potentially revealing additional genetic legacies from species such as Homo floresiensis and Homo luzonensis.
Background
For most of the 20th century, human origins were depicted as a tree: Homo sapiens emerged in Africa and replaced all other hominins without interbreeding. That model has been overturned by genetic studies showing that modern non-Africans carry Neanderthal and Denisovan DNA. Homo erectus was the first hominin to leave Africa, ranging across Eurasia nearly two million years ago and surviving in Indonesia until perhaps 100,000 years ago. The new study adds molecular data from a species too old for DNA analysis, providing direct evidence of gene flow between H. erectus and Denisovans.
What to Watch
- Whether the proteomic approach can be applied to fossils of Homo floresiensis and Homo luzonensis to detect their genetic legacy in modern populations.
- Future research into the functional consequences of the H. erectus-derived variant in present-day humans, which remains unknown.
- Additional studies that may identify further introgression events from other archaic "ghost" populations not yet sampled genetically.
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12 claims in this story checked against 1 source: 12 supported.
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- SupportedThe teeth are about 400,000 years old and suggest Homo erectus exchanged genes with Denisovans.Latest Science News -- ScienceDaily: “The new study indicates that Homo erectus exchanged genes (probably through interbreeding) with Denisovans in East Asia roughly 400,000 years ago.”
- SupportedHomo erectus may have left a small genetic trace in living people.Latest Science News -- ScienceDaily: “The lineage we once thought was a dead end has, it turns out, left a small but detectable trace in living human genomes”
- SupportedThe study reveals that interbreeding among archaic human lineages was routine.Latest Science News -- ScienceDaily: “What it really shows is that interbreeding between archaic human lineages was not exceptional. It was routine.”
- SupportedThe Nature study extracted ancient proteins from 400,000-year-old Homo erectus teeth.Latest Science News -- ScienceDaily: “the team extracted ancient proteins from the enamel of six teeth from three Chinese sites – Zhoukoudian [...] Hexian and Sunjiadong – all dating to around 400,000 years ago.”
- SupportedThe genetic trace may be present in living people in the Philippines, Papua New Guinea and across Southeast Asia.Latest Science News -- ScienceDaily: “some of that genetic legacy, it now appears, was passed on to living people in the Philippines, Papua New Guinea, and across south-east Asia.”
- SupportedThe research was by Qiaomei Fu of the Chinese Academy of Sciences and colleagues.Latest Science News -- ScienceDaily: “the one published in Nature by Qiaomei Fu from the Chinese Academy of Sciences and colleagues.”
- SupportedThe team analysed six specimens from Zhoukoudian, Hexian and Sunjiadong in China.Latest Science News -- ScienceDaily: “the team extracted ancient proteins from the enamel of six teeth from three Chinese sites – Zhoukoudian [...] Hexian and Sunjiadong”
- SupportedAll six specimens shared a previously unknown amino acid variant that confirmed their identity as east Asian Homo erectus and settled the Hexian classification debate.Latest Science News -- ScienceDaily: “All six specimens share a previously unknown amino acid variant [...] This variant clusters these east Asian H. erectus into a distinct group, confirming their identity and settling a long-running debate”
- SupportedA second variant was shared with Denisovans, and the corresponding genetic variant occurs at 21% in the Philippines and about 1% in India.Latest Science News -- ScienceDaily: “It also appears in Denisovans [...] The corresponding genetic variant turns up in living people at frequencies of 21% in the Philippines and about 1% in India”
- SupportedThe most reasonable interpretation is that Homo erectus passed the variant to Denisovans through interbreeding, and Denisovans later passed it to ancestors of modern Southeast Asians and Oceanians.Latest Science News -- ScienceDaily: “The most reasonable interpretation is that H. erectus populations in east Asia passed this variant to Denisovans through interbreeding, and Denisovans later passed it on to the ancestors of modern south-east Asians and Oceanians.”
- SupportedModern humans outside Africa carry roughly 2% Neanderthal DNA, while Papuans and Aboriginal Australians carry an additional 2–5% Denisovan ancestry.Latest Science News -- ScienceDaily: “Modern humans outside Africa carry roughly 2% Neanderthal DNA. Papuans and Aboriginal Australians carry an additional 2–5% Denisovan ancestry.”
- SupportedProteomics can recover biological information from fossils too old for DNA, and the approach could be applied to Homo floresiensis and Homo luzonensis.Latest Science News -- ScienceDaily: “it recovers meaningful biological information from H. erectus fossils far too old for DNA.”