New York, May 18 (IANS) A skull condition that has been believed to be a thing of the past due to poor diet among our ancestors not only still exists, but is fairly common among modern humans, new research has found.

The skull condition called cribra orbitalia (CO) makes bone inside the eye sockets porous. It is not known to cause any adverse health effects, but is generally regarded as being caused by iron deficiency anemia.

The condition has traditionally been used by anthropologists to assess diet and health in prehistoric populations. 

For example, the presence of CO could tell researchers that a population was not getting a sufficiently varied diet.

"But there's been a lot of debate about the prevalence of CO in modern populations, with some saying it had effectively disappeared," said study co-author Ann Ross from North Carolina State University in the US.

"We wanted to know if CO was still extant and, if so, how common it is in modern populations, relative to earlier eras," Ross noted.

For this study, the researchers looked at modern, historic and prehistoric human remains from South Africa, North America.

Altogether, the researchers evaluated data on 844 skulls -- 245 prehistoric, 381 historic (as recent as the early 20th century) and 218 modern.

The researchers found that CO was not only present in modern populations, but that it was not even uncommon.

For example, the researchers found that two of the five modern North American juvenile skulls evaluated in the study - 40 percent - had CO. And 15 of the 60 South African juveniles evaluated in the study - 25 percent - had CO.

Overall, the researchers found that 12.35 percent of modern North Americans and 16.8 percent of modern South Africans, across all age groups, had CO.

Both rates are higher than their historic counterparts. Only 2.23 percent of historic South African skulls evaluated had CO, and only 6.25 percent of historic North American skulls. Even the prehistoric North American skulls had a lower rate of CO, at 11.86 percent.

The study was published online in the journal Clinical Anatomy.

"We think the increased prevalence of CO in the modern skulls may be due to intestinal parasites in some populations and iron-poor diet," Ross noted.

"These findings drive home the fact that disadvantaged socioeconomic groups, and parts of the developing world, are still struggling with access to adequate nutrition," Ross added.​