Timeline of Human Evolution Now in Question Thanks to Unearthed Skull Found in China

A human skull discovered in 1990 is reshaping scientists’ understanding of human evolution.

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

When it was first found, the skull—named Yunxian 2—was crushed and deformed due to the fossilization process, making its significance difficult to discern.

“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. “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 found that the skull, which dates between 940,000 and over a million years ago, appears to be the oldest-known member of the evolutionary lineage that includes the Denisovans.

The Denisovans are an extinct subspecies of archaic humans, first identified in 2010 after a fossilized finger was discovered in the Denisova Cave in Siberia. They are thought to have lived across much of Asia.

This discovery also shifts 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.

While it was previously believed that these three species began diverging from a common ancestor around 700,000 to 500,000 years ago, the new study suggests that their common ancestry could date back as far as 1.32 million years.

“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 told CNN.