A new reconstruction of the Yunxian skull from central China is challenging the timeline of our species’ deep origins—and where those roots were laid. Using CT scans, 3D modelling and Bayesian analyses, researchers argue the ~1-million-year-old “Yunxian 2” cranium sits near the last common ancestor of Homo sapiens and Denisovan-related lineages, pushing their split back beyond 1.0 million years and potentially by around 400,000 years compared with some previous estimates. The study underscores both the promise and limits of morphology without ancient DNA. [1][3][5]

Key Takeaways

– Shows Yunxian skull dates to 940,000–1.1 million years, placing it near the last common ancestor of Homo sapiens and Denisovan-related lineages. [1][3] – Reveals a ~400,000-year earlier divergence date, pushing the Homo sapiens–Denisovan split back to >1.0 Ma based on morphology and Bayesian tip-dating. [3][5] – Demonstrates mixed anatomy: a large braincase with archaic facial traits, aligning Yunxian 2 as basal to the Asian Homo longi/Denisovan clade. [1][3][5] – Indicates the two Yunxian crania, discovered in 1989–1990 in China’s Hubei Province, were digitally reconstructed using CT scans and 3D modelling. [2][4] – Suggests bold implications yet urges caution: without DNA, morphology alone cannot prove origins; genetics are needed to test >1.0 Ma Asia–Africa scenarios. [1][2]

What the Yunxian skull reveals about a million-year timeline

The Yunxian site produced two crania—Yunxian 1 and Yunxian 2—discovered in Hubei Province in 1989 and 1990. Fresh digital reconstruction work focused on Yunxian 2, a more complete specimen that had been crushed and distorted. The new modelling restores its shape and context within the human family tree. The age is bracketed between 940,000 and 1.1 million years, anchoring this fossil close to a pivotal moment in human evolution. [2][3]

Anatomically, the reconstructed cranium shows a relatively large braincase paired with more archaic facial features, a mosaic of traits seen in several Middle Pleistocene Asian fossils. This combination led the team to place Yunxian 2 within, or just basal to, a lineage associated with Homo longi (“Dragon Man”) and Denisovans, implying a shared ancestry with the line leading to H. sapiens deeper in time than often portrayed. [1][3]

Crucially, the revised placement suggests the sapiens–Denisovan split occurred more than 1.0 million years ago. That timing pushes the divergence as much as ~400,000 years earlier than some genetic and fossil-based narratives, placing the Yunxian skull near the last common ancestor node for these branches. However, specialists stress that morphology alone cannot conclusively fix relationships without genetic data. [3][1]

Inside the reconstruction: CT scans, 3D models, and Bayesian clocks

Researchers used high-resolution CT scans and 3D modelling to virtually “uncrush” the Yunxian 2 cranium, correcting deformation and reconstructing missing parts. Geometric morphometrics quantified cranial shape, which was then compared across a large reference sample to assess affinities. This approach allowed the team to test whether Yunxian 2 fits better with Asian Middle Pleistocene forms, including the Homo longi/Denisovan-related clade, than with African or European counterparts. [4][5]

Phylogenetic analyses and Bayesian tip-dating were applied to integrate morphology with the fossil’s age. Tip-dating uses the specimen’s dated context to calibrate evolutionary trees, producing divergence time estimates that are consistent with the 940,000–1.1 million-year range for Yunxian 2 and indicating an earlier-than-expected split between the sapiens and Denisovan-related lineages. The modelled outcome places Yunxian 2 as basal to the Asian clade, not within the H. sapiens branch. [5]

The Natural History Museum’s commentary on the study emphasizes that both the H. sapiens and H. longi clades appear to have roots extending beyond the traditional Middle Pleistocene window. In other words, lineages leading to modern and Asian archaic humans may have already been distinct by more than a million years ago, reshaping the way scientists approach the “muddle in the middle” problem. [4]

Does this challenge an Africa-only origin for Homo sapiens?

The Yunxian skull’s age and placement invite a provocative question: does a near–last common ancestor found in China imply that H. sapiens arose outside Africa? Experts advise caution. The authors interpret Yunxian 2 as a sister to the modern human lineage rather than an early H. sapiens. Without DNA or proteins, the fossil cannot overturn the strong genetic case that anatomically modern humans evolved in Africa and later dispersed globally. [2][1]

What the Yunxian skull shows is that a sister group to H. sapiens—likely tied to Denisovans and the Homo longi complex—was present in East Asia around 1 million years ago. That placement pushes the timing of the split back beyond 1.0 Ma, but it does not prove where the H. sapiens branch itself originated or first diversified. The result is consistent with a deep, widespread network of early Homo populations across Africa and Eurasia before later speciation events. [5][3]

Chris Stringer, a leading British paleoanthropologist, calls Yunxian 2 “key” to sorting the Middle Pleistocene puzzle while reiterating that morphology can mislead without genetic anchors. In short: the find expands the geographic and temporal canvas for early human lineages but does not rewrite the African origins of H. sapiens on its own. Future work must target ancient DNA or proteomic evidence to resolve competing scenarios. [1][2]

Quantifying the ‘muddle in the middle’

The 940,000–1.1 million-year age range situates Yunxian 2 at the cusp of the early Middle Pleistocene, a period notorious for fragmentary fossils and complex regional variation. This “muddle in the middle,” long recognized by researchers, reflects the difficulty of classifying specimens that blend archaic and derived traits while populations moved and mixed across continents. The Yunxian skull’s refined date helps anchor this crucial interval with a well-contextualized specimen. [1][4]

Quantitatively, the new phylogenetic and tip-dated placement implies the sapiens–Denisovan split happened >1.0 Ma, an advance of roughly 400,000 years relative to some previous estimates, according to the study’s authors and independent commentary. Other expert summaries frame the shift as up to half a million years earlier, highlighting the uncertainty bands that inevitably accompany morphological datasets without DNA. Both figures underscore a major recalibration of early human divergence timing. [3][4]

This recalibration also affects how scientists view the Asian fossil record. If Yunxian 2 is basal to the Homo longi/Denisovan clade, then the roots of that group are older and deeper than the better-known Denisovan remains from Siberia and Tibet, which are far younger. The finding supports a scenario in which multiple long-lived lineages coexisted across Eurasia while the H. sapiens lineage was still differentiating, making simple linear models of human evolution increasingly untenable. [1][5]

What comes next for the Yunxian skull

Two priorities dominate expert wish lists: more fossils and more molecules. Morphological placement alone—however sophisticated the CT reconstruction and Bayesian modelling—cannot resolve the direction and tempo of evolutionary change with the confidence that genetic data provide. Several researchers, including coauthors and independent commentators, stress that obtaining DNA or proteins from Yunxian or related sites would test whether this lineage truly branched off before >1.0 Ma from H. sapiens. [1][2]

Meanwhile, additional CT-based reconstructions and expanded comparative datasets could refine the tree’s shape. Integrating newly found Asian fossils with African and European material from 1.2–0.8 Ma would further stress-test the claim that the sapiens–Denisovan divide stretches deeper into the Early–Middle Pleistocene transition. For now, the Yunxian skull stands as a critical calibration point, suggesting our lineage’s roots reach farther back in time than many models assumed—yet reminding us that definitive answers will require ancient biomolecules. [3][5]

Sources:

[1] Reuters – Ancient skull from China may shake up timeline of human evolution: www.reuters.com/science/ancient-skull-china-may-shake-up-timeline-human-evolution-2025-09-25/” target=”_blank” rel=”nofollow noopener noreferrer”>https://www.reuters.com/science/ancient-skull-china-may-shake-up-timeline-human-evolution-2025-09-25/

[2] The Guardian – Study of 1m-year-old skull points to earlier origins of modern humans: www.theguardian.com/science/2025/sep/25/study-of-1m-year-old-skull-points-to-earlier-origins-of-modern-humans” target=”_blank” rel=”nofollow noopener noreferrer”>https://www.theguardian.com/science/2025/sep/25/study-of-1m-year-old-skull-points-to-earlier-origins-of-modern-humans [3] The Washington Post – New look at ancient skull challenges timeline of human evolution: www.washingtonpost.com/science/2025/09/25/human-evolution-timeline-million-years/” target=”_blank” rel=”nofollow noopener noreferrer”>https://www.washingtonpost.com/science/2025/09/25/human-evolution-timeline-million-years/

[4] Natural History Museum (London) – Origin of our own species’ lineage pushed back by half a million years: www.nhm.ac.uk/discover/news/2025/september/origin-of-our-species-lineage-pushed-back-by-half-a-million-years.html” target=”_blank” rel=”nofollow noopener noreferrer”>https://www.nhm.ac.uk/discover/news/2025/september/origin-of-our-species-lineage-pushed-back-by-half-a-million-years.html [5] bioRxiv / Europe PMC (preprint) – The phylogenetic position of the Yunxian cranium elucidates the origin of Homo longi and the Denisovans: www.biorxiv.org/content/10.1101/2024.05.16.594603v1″ target=”_blank” rel=”nofollow noopener noreferrer”>https://www.biorxiv.org/content/10.1101/2024.05.16.594603v1

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