The oldest known example of cancer has been detected in the fossil of an early human who walked the Earth approximately 1.7 million years ago.
The discovery by British and South African scientists contradicts theories that cancer is a modern disease, predominantly caused by lifestyle factors.
Up until now, the oldest known human fossil associated with evidence of cancer dated back to around 3,000 BC.
But the new discovery of a bone near Johannesburg bolsters arguments that many cancers have a deep evolutionary history and are caused by factors beyond the control of humans.
A team of researchers from the Universities of Central Lancashire and Witwatersrand were scanning the fossils of prehistoric humans, which were found in the Swartkrans archaeological site, when they noticed that the inside of a toe bone was opaque.
“It was one of those moments when the light bulb goes on,” said Dr Patrick Randolph-Quinney, biological and forensic anthropology expert at Central Lancashire.
“The bone should have been hollow, and for it not to be hollow requires an expansion of some sort.
“So we compared it with modern biopsies of cancer patients and realised it was a malignant tumour.”
“We don’t know whether it was the cancer that killed him or something else.
“It would have certainly affected his mobility so it’s just as likely he was killed by a sabertooth tiger.”
The cancer has been identified as an osteosarcoma, an aggressive form of the disease which usually affects younger individuals in modern humans, and typically results in early death if left untreated.
Edward Odes, who co-wrote the paper, which is published in the South African Journal of Science, said: “Modern medicine tends to assume that cancers and tumours in humans are diseases caused by modern lifestyles and environments, but our studies show the origins of these diseases occurred in our ancient relatives millions of years before modern industrial societies existed.”
Archaeologists on a collaborating team also found a two million-year-old fossil of a benign cancer, which was discovered in the vertebrae of a child.
The oldest previously demonstrated human non-malignant tumour was found on the rib on a Neanderthal dated to around 120,000 years old.
The researchers said it was extremely rare for a tumour to be found in the back; they added that the fact it existed in a child contradicts assumptions that modern humans are more likely to exhibit tumours as a result of living longer than their ancestors.