A groundbreaking digital reconstruction of a million-year-old skull indicates that humans may have diverged from our ancient ancestors 400,000 years earlier than previously believed, and intriguingly, in Asia rather than Africa. This study, published on Thursday, is based on a reconstruction of a damaged skull discovered in China in 1990 and could potentially clarify the long-standing Muddle in the Middle of human evolution, according to the researchers involved.
The skull, referred to as Yunxian 2, was once thought to belong to the ancient human forerunner known as Homo erectus. However, advancements in modern reconstruction technologies revealed that the skull exhibits features more aligned with species previously believed to have emerged later in the human evolutionary timeline, such as the recently identified Homo longi and our own species, Homo sapiens.
Chris Stringer, an anthropologist at the Natural History Museum in London and a member of the research team, stated, "This changes a lot of thinking. It suggests that by 1 million years ago, our ancestors had already split into distinct groups, indicating a much earlier and more complex human evolutionary split than previously thought."
The research, published in the journal Science, utilized advanced techniques such as CT scanning, structured light imaging, and virtual reconstruction methods to create a complete model of Yunxian 2. The team also printed replicas using a 3D printer, enhancing their analysis of the skull.
The scientists relied on a similar skull for shaping their model and compared it to over 100 other specimens. The resulting model displayed a unique combination of traits, some reminiscent of Homo erectus, including a projecting lower face. However, other characteristics, like a seemingly larger brain capacity, are more closely related to Homo longi and Homo sapiens, as highlighted in the study.
If the study's findings are validated, they imply the existence of much earlier members of other early hominins, including Neanderthals and Homo sapiens. This challenges the long-held belief that early humans primarily dispersed from Africa. Michael Petraglia, director of Griffith University's Australian Research Centre for Human Evolution and not involved in the study, remarked, "There's a significant change potentially occurring here, where East Asia is now playing a crucial role in hominin evolution."
While the research team expressed excitement about their findings, experts not directly involved in the study have raised concerns. They caution that the results are likely to be contested due to the ongoing uncertainties surrounding the timeline of human evolution. Andy Herries, an archaeologist at La Trobe University, expressed skepticism, arguing that genetic analysis has shown that fossil morphology is not always a reliable indicator of human evolution.
Dr. Aylwyn Scally, an evolutionary geneticist at Cambridge University, stated that although the study's conclusions are plausible, they require further evidence for confirmation. "That picture is still quite unclear to us," he said. "If the conclusions of this research are supported by other analyses, particularly from genetic data, then we would start to be increasingly confident about it."
This study adds to a growing body of research that complicates our understanding of human origins. Homo longi, also known as Dragon Man, was only named as a new species and close human relative in 2021 by a team that included Stringer. The authors of the current study emphasize that fossils like Yunxian 2 highlight the complexity of our shared history and underscore how much we still have to learn about our origins.
