Neandertals living 120,000 years ago in what is now Croatia were not exposed to industrial chemicals, and they ate a diet free from processed foods. Yet, that didn't spare them from our modern-day maladies. Scientists have discovered the first known case of a tumor in the rib of a Neandertal man that dates to more than 120,000 years ago. The oldest known human tumor is from less than 4000 years ago.
"Relatively little is known about [tumor] prevalence in antiquity," says forensic anthropologist Douglas Ubelaker of the Smithsonian Institution in Washington, D.C., who was not involved in the new work. This result "is very useful for understanding the roots of this disease."
The bone—part of an upper left rib from an adult male Neandertal—was originally unearthed between 1899 and 1905 during the excavation of Krapina, a cave in northern Croatia which has yielded hundreds of ancient human remains. But the rib was misfiled and ignored for almost a century until, in 1999, it was briefly described in a list of specimens. More recently, anthropologist David Frayer of the University of Kansas, Lawrence, and colleagues began studying the pathologies of bones in the Krapina collections. It was immediately clear that the rib fragment—specimen 120.17 in the collection—wasn't normal. "The bone is broken away so you can look into the marrow chamber, where even in a child, you'd expect to see spongy bone," Frayer says. "But in this rib, instead of there being a mesh of bone there, it's completely vacant."
Even with the naked eye, the scientists recognized that empty area of bone indicated a tumor had once sat there. But to get more details on its size and shape, the researchers turned to x-rays and CT scans. These studies revealed that the void's physical characteristics—the type and location of missing bone—were consistent with a fibrous dysplastic neoplasm, a tumor caused by a bone growth disorder, the scientists report online today in PLOS ONE. Now, fibrous dysplastic neoplasms are one of the most common causes of tumors in the ribs and can cause bone fractures and pain.
"Unfortunately we don't have more of this particular skeleton," Frayer says. As a result, the researchers can't determine more details on the individual with the tumor, like whether his other bones had tumors and whether he had symptoms of systemic diseases that can occur alongside the tumors. Researchers also can't draw inferences from a single sample on the frequency of tumors in the Neandertal population, he says.
"There's always a temptation to try to read more into a lesion than one can confidently interpret," Ubelaker says. "But these authors did a splendid and careful job of taking the evidence only as far as it will go in terms of differential diagnosis."
The causes of fibrous dysplastic neoplasms aren't now understood. Knowing that they have been present in human relatives since prehistoric times could shed light on how the tumors co-opt an ancient molecular pathway in our cells to grow. But it will take more examples of ancient bone tumors to draw broader conclusions, the researchers say.