A digital reconstruction of a million-year-old skull has revealed that humans may have diverged from their ancient ancestors 400,000 years earlier than previously thought, and in Asia, not Africa, according to a new study published Friday.
The study's authors explained that these conclusions are based on a reconstruction of a fractured skull discovered in China in 1990, and could resolve a mystery called the "intermediate chaos," which has long shrouded human evolution.
The skull, dubbed "Yunxian 2," was previously thought to belong to a human ancestor known as Homo erectus.
But new reconstruction techniques used by a team of researchers have revealed features closer to species previously thought to have existed later in human evolution, including the recently discovered Homo erectus and Homo sapiens, the modern-day Homo sapiens.
Chris Stringer, an anthropologist at London's Natural History Museum who was part of the research team, said the discovery "changes a lot of ideas."
"This shows that our ancestors split into distinct groups a million years ago, meaning that the human evolutionary split is much older and more complex than previously thought," he added.
If the findings are correct, they suggest the existence of individuals much older than other early hominins, including Neanderthals and Homo sapiens.
But they also undermine long-held assumptions that early humans spread out of Africa, according to Michael Petraglia, director of the Australian Centre for Human Evolutionary Research at Griffith University, who was not involved in the study.
"These findings could potentially represent a significant shift, if East Asia plays a major role in hominin evolution," Petraglia told AFP.
The study, published in the journal Science, used advanced computed tomography, structural light imaging, and virtual reconstruction techniques to model the entire skull of Yanxian 2.
The scientists relied partly on another similar skull to form their model and then compared it to more than 100 other specimens.
The resulting model "shows a diverse mix of features," the study reported, some similar to Homo erectus, including a protruding lower face.
But other aspects, including a seemingly larger brain capacity, are closer to Homo erectus and Homo sapiens, according to the researchers.
"Yanxian 2 may help resolve the so-called 'intermediate stage chaos,'" Stringer said in a statement, referring to confusion arising from a collection of human fossils dating back between 1 million and 300,000 years.
"Fossils like Yanxian 2 show that we still have much to learn about our origins," Stringer said.
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