The part of the skull showing prematurely fused sutures: (A) The first segment is completely fused. (B) The second segment is fused, but still noticeable. (C) The lambdoid portion of the suture is completely open (Image: National Academy of Sciences, PNAS)

A recently unearthed ancient human skull shows signs of a disorder that might have caused mental retardation. This offers the earliest evidence that ancestors of Homo sapiens did not abandon young with severe birth defects.

The 500,000-year-old skeleton belonged to a five to 12-year-old child who suffered from craniosynostosis. The rare congenital condition occurs when two of the flat bones that make up the skull fuse together along their margins (sutures) too early during fetal development, hindering brain growth.

Spanish researchers discovered the first pieces of the skull near Atapuerca, Spain, in 2001, but they only recently pieced enough of it together to make a conclusive diagnosis.


“We were sure we had evidence of a real pathology,” says Ana Gracia, a palaeoanthropologist at Complutense University in Madrid, who led the new study. “It’s obvious – you only have to look at the cranium.”

Different appearance

The child suffered from a form of craniosynostosis that occurs in about 1 in every 200,000 children.

He or she was a member of the species Homo heidelbergensis, – early humans that lived in Europe up to 800,000 years ago and may have given rise to Neanderthals.

The discovery marks the earliest example of a human skeleton with signs of a physical deformity that that might have made the individual dependent on others for survival.

Most animals, including primates, sacrifice or abandon young born with crippling deformities, Gracia says. It’s impossible to know whether the child suffered from any cognitive problems, but he or she would undoubtedly have looked different from family and friends, she says.

‘Not clear-cut’

“The obvious conclusion is that [this child] was being helped by other members of the social group,” says Erik Trinkaus, a paleoanthropologist at Washington University in Saint Louis, Missouri.

However, Matthew Speltz, a psychologist at the University of Washington in Seattle, says the link between craniosynostosis and cognitive problems is not so clear-cut. Speltz is leading an ongoing study to track the development of children born with various forms of the condition.

His team has found that children with craniosynostosis are more likely than other kids to have cognitive and motor problems. But the condition is by no means a guarantee of severe learning difficulties. “There might be a slight increased risk of mental retardation,” he says.

Journal reference: Proceedings of the National Academy of Science (DOI: 10.1073/pnas.0900965106)