A third skull is discovered in China possibly belonging to the Homo erectus species

Vialet worked on the first two skulls, commonly referred to as Yunxian 1 and 2. However, those relics were distorted after millennia underground, whereas the third skull, Yunxian 3, is in mint condition.

Members of Homo erectus

In 2010, Vialet and her colleagues speculated that the Yunxian 2 skull was a member of the archaic human species Homo erectus that lived between 1.1 million and 800,000 years ago.

The Yunxian 3 skull is currently still half-buried in an upright position. Despite this, researchers have uncovered the forehead, including the brow ridge and eye sockets, as well as the top, back and left cheekbone of the skull.

It is not yet known whether teeth or a lower jawbone are attached to the skull, says Gao Xing at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, who is leading the excavation.

Vialet says that the Yunxian 1 and 2 skulls share some features with older Javanese fossils and others with younger Homo erectus fossils from mainland Asia. Like the Javanese fossils, they are large, big-brained skulls. But she says that they are less heavily built, a characteristic that usually indicates a more modern individual.

Researchers have found Homo erectus remains at more than a dozen sites across China. Vialet says that the ancient humans at Yunxian could be the ancestors of some of these populations, but their skulls bear distinct features that set them apart.

Same locations, different attributes

However, just because they have been found in the same location does not mean they are from the same sources. Yameng Zhang, a palaeoanthropologist at Shandong University, told nature magazine that the Homo erectus fossils found in China are vastly different and that the reasons for that remain unknown. 

He speculates two theories: that each population evolved independently in Asia or that they could have been the result of multiple waves of expansion out of Africa.

However, an answer to this dilemma may soon be found “More complete Chinese Homo erectus like Yunxian 3 are crucial to answer this question,” he added.

To ponder this mystery, Vialet is currently comparing Yunxian 2 with European hominin fossils.  Furthermore, Clément Zanolli at the University of Bordeaux, France notes that the Yunxian 3 skull’s teeth, especially its molars, could be helpful for discerning evolutionary relationships with other early humans.

The Yunxian 3 skull still needs a few months to be excavated. Once that is done, dating it will be crucial. But it won’t be an easy task.

Since China lacks volcanic sediments that can be dated by analyzing the amounts of radioactive isotopes in the rock, Wei Wang, a geochronologist at Shandong University, says that hominin fossils in China are more complicated to date accurately than fossils in Africa.

In addition, small animal fossils surrounding the Yunxian 3 skull are slowing the extraction process as properly maintaining these specimens is crucial to pinpointing the age of the Yunxian 3 skull. What will the skull reveal once fully excavated? Only time will tell.