A tumor found in a Neanderthal specimen more than 120,000 years old may give scientists insight into the origins of cancer.
The rib tumor, which was an abnormal bone growth known as a fibrous dysplasia, is consistent with a kind of cancer that is found in modern-day people. It is one of the most common bone tumors in humans, the researchers noted.
"Evidence for cancer is extremely rare in the human fossil record. This case shows that Neanderthals, living in an unpolluted environment, were susceptible to the same kind of cancer as living humans," co-author David Frayer, a professor of biological anthropology at the University of Kansas, said in a press release.
The part was one of 876 fragments found in a rock shelter in Krapina, Croatia, in the late 1800s, and is thought to belong to one of a dozen individuals. Scientists have speculated that the bones were so fragmented either because the Neanderthals were cannibals or they were eaten by carnivorous animals, the Smithsonian reported.
The tumor was found by completing an X-ray and CT scan on a rib bone. The images showed a upward-protruding lesion on the rib that could not be an injury because there was no other traumas visible on the back of the rib.
Because the growth was found in an incomplete specimen, scientists will not be able to speculate about how the tumor affected the health of the Neanderthal.
The tumor was surprising because Neanderthals are estimated to have had half the lifespan of modern humans in developed countries, meaning this individual developed his issues earlier in life.
"Most cancers affect people when they get older, and most Neanderthals and earlier populations died before they got old. So this was really exciting to see," Frayer explained to National Geographic.
In addition, Neanderthals lived in completely different environmental factors so known carcinogens may not have been present.
"They didn't have pesticides, but they probably were sleeping in caves with burning fires," Frayer explained. "They were probably inhaling a lot of smoke from the caves. So the air was not completely free of pollutants -- but certainly, these Neanderthals weren't smoking cigarettes."
Before finding this tumor, the oldest evidence of cancer was between 1,000 to 4,000 years old.
"Some people think that cancer is only a modern disease, but there's evidence from fossils, bones and mummies that it's actually many thousands of years old," Kat Arney, science information manager at Cancer Research U.K., told the BBC. "So this discovery isn't entirely surprising, even though such finds are very rare, but it helps to shed light on the complex history of cancer in humans and our ancient relatives."
The study was published in PLoS ONE on June 5.