A Bone-Deep Kinship

The researchers were hopeful that they might be able to lighten the image or increase the contrast to make out some of the bone’s detail, but upon returning to Penn and digitizing the X-rays, Monge had no luck. “I realized that basically there was no detail on it at all, no matter how you manipulated it,” she recalls.

Unfortunately, other research projects—as well as ongoing political turmoil in the region—kept the team from returning to Zagreb for more than a decade. Finally, in the late 1990s, with the atlas still unpublished, another Penn collaborator, Alan Mann, now at Princeton University, drove to Croatia from France, where he ran a field school for students excavating Neanderthal sites, to get a better X-ray of the rib fragment. He brought the film back to Monge—by that time a curator at the Penn Museum of Archaeology and Anthropology—who digitized it as she had the rest of the collection. The quality still wasn’t great, but it was good enough, they decided, and they published The Krapina Hominids: A Radiographic Atlas of the Skeletal Collection in 1999.

But Kricun, a bone radiologist, couldn’t get that rib fragment out of his mind. Studying the image they had just published, Kricun noted that the normally hard exterior, called the cortex, was very thin, and that the bone lacked almost all of the spongy interior—which explained why the radiation levels used for similar specimens turned out to be way too high for this hollowed-out fragment. He suspected the malformed bone was evidence of a fibrous dysplasia, a rare type of benign tumor occasionally found in the ribs and other bones of modern humans.

To confirm his suspicions, however, the team needed more information. So last year, the researchers asked colleagues at the University Hospital in Zagreb to take more X-rays, and persuaded the Croatian Natural History Museum’s Davorka Radovčić to conduct micro-CT scans. “We wanted to have good color photos of it,” says collaborator David Frayer, a paleoanthropologist at the University of Kansas. The CT scans involved “more than 1,000 cuts in the imaging, so that it’s a very accurate, detailed account of what the cavity looks like [that] you can’t really get from a 2-D X-ray.”

Sure enough, the results confirmed that the individual, likely an older teen or young adult, had the oldest documented case of fibrous dysplasia by more than 100,000 years. “I’ve never seen anything like this and I’ve looked at lots of skeletons,” says Frayer, who has worked with the Krapina collection for more than 2 decades.

Human paleontologist Fred Smith of Illinois State University in Normal says that, while he is not surprised by the existence of a Neanderthal tumor of this sort, the finding “underscores in some ways the fact that these Neanderthals basically [had] the same kind of biology that we have and they [were] subject to the same kind of growth and developmental processes, even abnormal.”

“It is important to know that the very same kind of change associated with this tumor is something that we share with Neanderthals,” agrees Monge. “That has a very, very deep history within the human lineage and very much ties us—in terms of disease pathological processes—to Neanderthals.”