Unearthed Human Skull Suggests New Human Evolution Timeline

A human skull found in 1990 is now changing scientists’ understanding of human evolution. 

In a study published in the journal Science on Sept. 25, researchers determined that an ancient skull unearthed in China’s Hubei Province over 30 years ago may push back knowledge of the emergence of the human species by 400,000 years.

When discovered, the skull — called Yunxian 2 — was crushed and deformed as a result of the fossilization process, making it difficult for researchers to understand its significance. 

“We decided to study this fossil again because it has reliable geological dating and is one of the few million-year-old human fossils,” the study’s first author, Xiaobo Feng, a professor at Shanxi University in China, told CNN in a statement. “A fossil of this age is critical for rebuilding our family tree.”

Paleoanthropologist Xijun Ni of Fudan University and the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, digitally reconstructed the fossil and determined that the skull, which is between 940,000 and over a million years old, seems to be the oldest-known member of the evolutionary lineage that includes the Denisovans.

The Denisovans are an extinct subspecies of archaic humans, which were discovered in 2010 after researchers found a fossilized finger in the Denisova Cave in Siberia. They are believed to have lived across much of Asia. 

As a result, the timeline for Homo sapiens and Homo neanderthalensis — archaic humans who disappeared from Europe and Central Asia around 40,000 years ago and are known to have lived alongside the Denisovans — has also been shifted. 

While it was initially believed that the three species began to diverge from a common ancestor around 700,000 to 500,00 years ago, the new study indicates that common ancestry could actually date back as far as 1.32 million years.

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“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,” coauthor Chris Stringer explained to CNN.