A prehistoric skull condition thought to have gone extinct has been found to not only still exist today, but to be widespread among some populations. Scientists found the condition, cribra orbitalia (CO), is relatively common in North Americans and South Africans.

In people with CO, the bone inside the eye sockets becomes porous. Though it is not known to have any adverse health impact, scientists believe it is caused by an iron-deficiency due to anaemia.

A study, published in the journal Clinical Anatomy, assessed the prevalence of CO in prehistoric, historic and modern populations, to examine changes in prevalence overtime.

"There has been a lot of debate about the prevalence of CO in modern populations, with some saying it had effectively disappeared," says Ann Ross from Forensic Sciences Institute at NC State and one of the study authors. "We wanted to know if CO was still extant and, if so, how common it is in modern populations, relative to earlier eras."

Examining skeletons

The team of scientists looked at 844 skeletons from two different regions: the north-eastern US and the central Gauteng area of South Africa. This sample was constituted of prehistoric, 381 historic and 218 modern skeletons.

Looking at the skeletons' eye sockets, the researchers established that about 12% of modern North Americans and 16.8 % of modern South Africans, across all age groups, had CO. This was particularly the case in "juvenile skeletons": 40% of North American juvenile skulls and 25% of South African juveniles presented signs of CO. It is possible however that these numbers may be a little biased.

"We thought we might see some CO, but not to the extent that we did," Ross says. "The high rates may stem from the fact that these remains were part of forensic cases – there were often related to cases of homicide or neglect. These cases are not representative of health for all children."

More interesting perhaps, the scientists note that CO rates in modern humans are higher than the ones evaluated in historic skulls. Across all age groups, 2.23% of historic South African skulls evaluated had CO, and only 6.25% of historic North American skulls.

Prehistoric skulls had a higher rates of CO than historic skulls, but lower than modern skulls roughly 11.8% of North American prehistoric skeletons had CO.

Decline in health

These results suggest that health may have declined for some groups in recent times, with some individuals presenting potentially debilitating low levels of iron.

"We think the increased prevalence of CO in the modern skulls may be due to intestinal parasites in some populations and iron-poor diet.These findings drive home the fact that disadvantaged socio-economic groups, and parts of the developing world, are still struggling with access to adequate nutrition", Ross says.