The ‘large head’ people: Scientists uncover a lost human species in Asia

The story begins in the 1970s when researchers unearthed a collection of 21 fossil fragments representing 16 different individuals at the Xujiayao site. But it wasn’t until recent comprehensive analysis that scientists realized just how unique these remains were. The most striking feature? A cranial capacity of approximately 1,700 milliliters – significantly larger than both their predecessors and many modern humans.

To put this in perspective, the average modern human brain size is between 1,090 to 1,880 milliliters, and our famous cousin, the Neanderthals, ranged from 1,120 to 1,740 milliliters. What makes the Xujiayao findings so remarkable is that they possessed such large brains during a period when most other human species had considerably smaller cranial capacities.

The Xujiayao humans were like evolution’s master mixologists, combining features from various human species in unexpected ways. They maintained some primitive characteristics typical of early East Asian humans, such as thick skull bones and distinctively shaped teeth. Yet they also showed more advanced features similar to those found in Neanderthals and modern humans. It’s as if nature decided to experiment with different human traits, creating a unique cocktail of characteristics never seen before or since.

These ancient people lived in what is now northern China during a major glacial period when temperatures were approximately 4°C lower than today. The landscape was covered in forest steppe vegetation, and evidence suggests they were skilled hunters, particularly of horses. Thousands of stone balls found at the site may have served as projectile weapons for hunting, and numerous animal bones bearing cut marks indicate they were proficient at butchering their prey.

One of the most fascinating aspects of the discovery is what it tells us about human diversity in ancient East Asia. The traditional view of human evolution as a straight line from primitive to modern is being replaced by a much more complex picture. The Xujiayao fossils show that multiple human species coexisted and likely interbred, creating a rich tapestry of human diversity that we’re only now beginning to understand.

The research team, led by scientists from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and the University of Hawai’i at Manoa, conducted extensive comparative analyses with other human fossils from the same period. They found that while the Xujiayao humans shared some features with other known species, their unique combination of characteristics set them apart as a distinct group.

The discovery also challenges our understanding of brain evolution. The presence of such large-brained individuals so early in human history suggests that brain size expansion wasn’t a simple linear progression. Instead, different human groups may have developed larger brains independently and for different reasons.

Perhaps most intriguingly, the Xujiayao humans appear to be related to the mysterious Denisovans, known primarily from DNA evidence and a few fossil remains found in Siberia. This connection suggests a widespread population of large-brained humans existed across much of eastern Asia during the late Quaternary period.

“I see the name Juluren not as a replacement for Denisovan, but as a way of referring to a particular group of fossils and their possible place in the network of ancient groups,” writes anthropologist John Hawks, who did not take part in this study. “In my opinion, Bae and collaborators have a good case for distinguishing the Chinese fossil record from the fossils from Africa and western Eurasia across this time.”

Like pieces of an ancient puzzle, each new fossil discovery helps complete our picture of human evolution. The Xujiayao findings, published in the journal PaleoAnthropology, remind us that our family tree has many branches, some of which we’re only now beginning to discover. These ancient “large head people” may have disappeared from Earth, but they’ve left us with big questions about human evolution that are sure to keep scientists’ heads spinning for years to come.