Reconstruction of the Yunxian Homo erectus (Credit: Xiaobo Feng)
Stone tools discovered in China date back as far as 2.4 million years. The oldest confirmed human fossils from the same region? Only 1.77 million years old. That gap, now significantly narrowed by new research, leaves one question stubbornly unanswered: who, or what, was already there?
A study recently published inScience Advanceshas pushed back the age of three ancient skulls found at a site in Hubei Province, China, called Yunxian, to approximately 1.77 million years old. That makes Yunxian the oldest confirmed, in-placeHomo erectusfossil site in all of eastern Asia, pushing the site back by roughly 700,000 to nearly a million years from its previous estimate. But the finding also makes the mystery of China’s earliest inhabitants harder to ignore. Ancient stone tools at other Chinese sites predate the Yunxian skulls by hundreds of thousands of years, and no fossil evidence has yet identified who made them.
Homo erectus, which translates roughly to “upright man,” was an early human relative that walked on two legs, used stone tools, and spread across Africa, Europe, and Asia over more than a million years.
Yunxian’s revised age puts it remarkably close in time to Dmanisi in the country of Georgia, currently the oldestH. erectussite in all of Asia at roughly 1.78 to 1.85 million years old. That proximity across thousands of miles of terrain raises its own set of questions about how quickly theseancient humansmoved.
The real puzzle centers on what came before Yunxian. Archaeological sites at Xihoudu in northern China have yielded stone tools dated to approximately 2.4 million years ago. Shangchen, another Chinese site, shows evidence of tool use going back about 2.1 million years. Both sites predate the Yunxian skulls by hundreds of thousands of years, yet neither has produced any hominin fossils. The authors of the new study note that as dates for fossil sites like Yunxian continue to be pushed back, the gap between the earliest known archaeology and the earliest known humanfossils in Chinais quickly narrowing. But it has not closed. Someone, or something, appears to have been chipping stone in China long before the arrival of any human ancestor yet identified in the fossil record there.
One possibility is thatH. erectusarrived earlier than Yunxian’s 1.77 million-year date suggests, and that confirming fossils simply have not been found yet. Another is that a different, as-yet-unidentified hominin made those earlier tools, a species that precededH. erectusin the region before vanishing from the record. The study’s authors acknowledge both possibilities, noting that the earliest Asian archaeological sites now predate the traditionally accepted appearance ofH. erectusat roughly 1.9 million years ago, which raises the prospect of “alternative hominins as the possible earliest occupants of Asia.”
Getting a reliable date from sediment nearly two million years old is no small feat. Earlier attempts at Yunxian used magnetic field analysis and radiation-based dating of animal teeth, producing a wide, inconsistent range of estimates. This study used a well-established burial dating method, one that tracks tworadioactive elementsnaturally absorbed by quartz gravel while it sits at the surface. Once that gravel gets buried underground, the elements decay at known rates, functioning as a natural clock. By analyzing quartz samples pulled directly from the skull-bearing sediment layer, the team landed on an age of 1.77 million years. A second set of samples from a deeper layer came back at a matching 1.76 million years.
What sets Yunxian apart from other contenders for oldestH. erectussite in China is context. At Yuanmou, another well-known Chinese site with potentially ancient fossils, the specimens were collected from the surface rather than from intact ground, casting doubt on any age estimates tied to them. At Yunxian, theskullswere found embedded in an identifiable sediment layer rich with animal bones and more than 500 stone tools. Several of the very quartz samples used in the dating even bore traces of toolmaking, directly tying the age estimate to evidence of hominin presence.
Three skulls have now been recovered at Yunxian. The first two were severely compressed by sediment over the ages, complicating their study. Earlier analyses suggested they look different fromH. erectusremains found at Zhoukoudian cave near Beijing, hinting at variation across the species in ancient China. A third, reportedly better-preserved skull turned up during excavations in 2021 and 2022, found in the samesediment layer.A full analysis of that specimen has not yet been published, leaving the most complete picture of who these individuals were still out of reach.
Source: Drudge Report
