Ancient skull upends timeline of human origins, pushing Homo sapiens beyond 1 million years old

A fossil skull known as Yunxian 2, unearthed in Hubei Province, China, has prompted a major update to the timeline of human evolution. Dating to about one million years ago, the heavily deformed cranium was re-examined by an international team using advanced imaging and reconstruction techniques. The study, published in Science, argues that Yunxian 2 is not simply a Homo erectus specimen but a member of a broader longi-related clade connected to later Chinese fossils and to Denisovans, a lineage thought to have contributed DNA to some modern populations. The researchers say the reanalysis suggests that the early human family tree was already more complex and temporally extended than previously thought, with distinct lineages diverging earlier than once accepted. The work is led by scientists from Fudan University in Shanghai and the Chinese Academy of Sciences in Beijing, with contributions from Chris Stringer of the Natural History Museum in London.

Dating and reconstruction of Yunxian 2 have been complemented by a comparative approach that includes a newly reconstructed model derived from Yunxian 1 and 104 other high-quality fossil specimens. The goal was to estimate what the skull would have looked like when intact and to test its affinities against known species. The researchers note that Yunxian 2 bears some primitive traits compatible with Homo erectus, such as a large, robust braincase and a pronounced brow ridge, but it also carries derived features in the face and the posterior braincase that align more closely with later groups, including Homo longi and Homo sapiens.

The study undertook a careful reconstruction of Yunxian 2, incorporating small elements from Yunxian 1, another crushed skull from the same site excavated in 1989. The team then compared the reconstruction to 104 fossil specimens and replicas to assess similarities and differences. The results indicate that Yunxian 2 is not a straightforward Homo erectus specimen but an early member of the longi lineage, a group already linked to the Denisovans in Asia. The team emphasizes that while the skull shares some archaic traits, its overall pattern of variation points to a lineage that predates the classic Homo sapiens–Homo erectus split.

"Our research reveals that Yunxian 2 is not Homo erectus, but an early member of the longi clade and linked to the Denisovans," Stringer said. "This changes a lot of thinking because it suggests that by one million years ago, our ancestors had already split into distinct groups, pointing to a much earlier and more complex human evolutionary split than previously believed." The investigators stress that they are not yet prepared to classify Yunxian 2 as Homo longi pending further evidence, including analysis of a third skull from the site—Yunxian 3—expected to serve as an important test of the new reconstruction.

The findings contribute to a radically updated view of human evolution. In the last 800,000 years, the researchers say, most large-brained humans trace to five major branches: Asian erectus, heidelbergensis, longi, sapiens, and neanderthalensis. They argue that these groups were already diverging from one another more than a million years ago, a significantly deeper time frame than previously assumed.

The study also reinforces a long-standing narrative about Homo sapiens origin and dispersal. While Homo sapiens are believed to have evolved in Africa and later migrated out of the continent around 60,000 to 70,000 years ago, the expansion into Europe and Asia occurred in stages where interactions with other hominins occurred. The new timeline underscores how interbreeding with archaic populations, including Neanderthals and Denisovans, left enduring marks on the human genome. Modern Denisovan DNA, for example, remains detectable in populations across parts of Asia and Oceania, with several studies indicating distinct Denisovan ancestry in different regional groups.

The Denisovans, a sister lineage to the Neanderthals, are known primarily from remains in Siberia and parts of Asia. Genetic traces have appeared in modern humans across Oceania and parts of East Asia, suggesting complex interbreeding events that may have included multiple dispersal waves. The Science paper’s authors point to this growing mosaic of ancestry as evidence that early human populations did not follow a single, linear path but rather diversified into multiple lineages that circulated and interacted across the continent.

Looking ahead, the team plans to extend the analysis by incorporating additional data sources and fossils to refine the emerging picture. Stringer said the forthcoming study of Yunxian 3, along with new fossil finds, should help determine whether Yunxian 2 truly belongs to the longi lineage or reflects an intermediate position within the broader early Asian human family.

The evolving story of human origins continues to be shaped by both fossil discoveries and advances in imaging, 3D reconstruction, and ancient DNA analysis. While this new work does not overturn established milestones—such as Africa as the cradle of Homo sapiens or the broad outline of out-of-Africa migration—it adds a layer of complexity to the earliest chapters of the human family tree and invites a reassessment of how and when lineages split and spread across the globe.