An ancient Neandertal rib bone reveals that the first cases of cancer occurred more than 120,000 years ago.

Anthropologists have found signs of neoplastic bone disease—specifically a bone tumor—in the remains of one of man’s closest relatives, according to newly published research.

There wasn’t enough evidence to determine whether the cancer killed this specific Neandertal, but a team of experts at the University of Pennsylvania and other academic institutions recently discovered signs of cancer in his remains, which date back to more than 120,000 years ago.

“Evidence for cancer is extremely rare in the human fossil record,” David Frayer, a professor of biological anthropology at the University of Kansas, said in a press release. “This case shows that Neandertals, living in an unpolluted environment, were susceptible to the same kind of cancer as living humans.”

Prior to the new discovery, signs of cancer in the human fossil record dated back only to between 1,000 and 4,000 years ago, according to the research, published this week in PLOS One.

Researchers involved in the project did not respond to calls seeking additional information.

The bone sample, labeled Krapina 120.71, is a fragment of a left rib and shows evidence of a tumor the researchers believe was caused by fibrous dysplasia, a bone disorder usually diagnosed in children.

The bone was discovered in a rock shelter north of Zagreb, Coatia, during a large-scale excavation beginning in 1899 that yielded more than 900 human bones, along with animal bones and stone tools.

Neandertals—named for Neander’s Valley where the species was first discovered—didn’t experience many of the modern-day causes of cancer: tobacco smoke, nuclear radiation, etc.

Neandertals had average life spans that were likely half as long as those of modern humans in developed countries, and they were exposed to a different set of environmental factors.

“It is recognized that environmental changes wrought by humans, compounded by population expansion, have resulted in an increase in the types and the intensification of the pollutants within the environment, many of which are directly associated with neoplastic disease and were not part of environments in the past,” the researchers wrote.

However, Neandertals were still exposed to UV radiation from the sun, smoke inhalation (from fires needed to stay warm), and cancer-causing mutations in their genes, which play a part in modern-day cancer cases as well.

Though the cause of this Neandertal’s cancer may never be known, his case offers insight into how even our prehistoric relatives were affected by a disease that continues to blight mankind.

“Cases of neoplastic disease are rare in prehistoric human populations,” the researchers concluded. “Against this background, the identification of a more than 120,000-year-old Neandertal rib with a bone tumor is surprising, and provides insights into the nature and history of the association of humans to neoplastic disease.”