North Carolina State University

Researchers found that craniofacial differences between contemporary men and women are less pronounced than they were in the 16th century.

Female faces have gotten larger in Spain over the past four centuries while those of men have stayed essentially the same, according to a new study that suggests differences in the craniofacial features of men and women have become less pronounced.

The finding is based on the comparison of more than 200 skulls dating to 20th- and 16th-century Spain, as well as approximately 50 skulls from 20th-century Portugal using a state-of-the art 3-D shape analysis system.

The distinction between the males and females could be because diet and environmental changes impact males and females differently, and because females are more affected in the face than males, Ann Ross, an anthropologist at North Carolina State University, explained to me today.

"Females are the ones that are changing," she said. "There appears to be a size-related change over time in the Spanish population, and that's probably due to improved nutrition."

The National Museum of Natural History's Douglas Ubelaker, co-author of the study, told me that genetics and gene flow through the population are also factors in the changes the team found. "What we're trying to do is just document that it occurred and give some sense of where it is headed," he said.

The sexual differences among the faces were similar between 20th-century Spanish and Portuguese populations, implying that the standards for identifying sex in Spanish skulls can be applied regionally.

This information, in turn, can be used to help anthropologists studying population change, or even a crime investigator attempting to identify a body based on a partial skeleton.

"Because of the sophisticated databases that can now be built on these samples and others, we are in a much better position to make the right call when the forensics case shows up," said Ubelaker, who is a consultant on such cases.

A paper describing the research will appear in the journal Forensic Science International.

More stories on changing faces:

• Typical face is Chinese for now
• Ideal beauty a matter of millimeters, study says
• It's not just our skin that ages, face bones change too
• Humans still evolving as our brains shrink

John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).