A fossilised human foot bone from South Africa dating back 1.7 million years contains the oldest evidence of malignant cancer on record.
Scientists discovered signs of osteosarcoma, an aggressive form of bone cancer, in a metatarsal - one of the five long foot bones that connect to the toes.
Experts do not know precisely what species the bone belonged to, but are certain it was an ancient human and not an ape.
The find challenges the view that cancer is a “modern” disease linked to unhealthy lifestyles and environmental pollution.
An accompanying paper published in the same journal, the South African Journal of Science, documents an even older benign tumour.
This was found in the vertebrae of a child who lived almost two million years ago, and is the oldest tumour ever seen in a human fossil.
Researcher Edward Odes, from the University of the Witwatersrand, South Africa, who took part in both studies, said: "Modern medicine tends to assume that cancers and tumours in humans are diseases caused by modern lifestyles and environments.
“Our studies show the origins of these diseases occurred in our ancient relatives millions of years before modern industrial societies existed.”
The foot bone was unearthed from the Swartkrans archaeological site, near Johannesburg.
Osteosarcoma is an aggressive cancer which usually affects younger individuals among modern humans and if left untreated leads to early death.
Dr Bernhard Zipfel, a University of the Witwatersrand expert on the feet and locomotion of early humans, said: "Due to its preservation, we don't know whether the single cancerous foot bone belongs to an adult or child, nor whether the cancer caused the death of this individual, but we can tell this would have affected the individuals' ability to walk or run.
“In short, it would have been painful.”
Benign tumour
The benign tumour was found in “Karabo”, a child belonging to the ape-like hominin species Australopithecus sediba, from the Malapa fossil site in South Africa.
The previous oldest tumour was discovered in the rib of a Neanderthal from 120,000 years ago.
Dr Patrick Randolph-Quinney, from the University of the Witwatersrand and the University of Central Lancashire, who also investigated both finds, said: “The presence of a benign tumour in Australopithecus sediba is fascinating, not only because it is found in the back, an extremely rare place for such a disease to manifest in modern humans, but also because it is found in a child.
“This, in fact, is the first evidence of such a disease in a young individual in the whole of the fossil human record.”
Both diseases were diagnosed using state-of-the-art X-ray imaging.
Hannah Birkett, from the Bone Cancer Research Trust, said: "This discovery is really exciting for osteosarcoma and the field of primary bone cancer research as a whole.
“It further solidifies what we already know about the pathology of osteosarcoma and its development from the cells which are working to produce bone.
“Modern lifestyles and environmental factors loom large in people’s perceptions of the cause of cancer, and this finding reconfirms the importance of considering other factors, such as bone growth.
“This discovery will hopefully open new doors into investigating the cause of osteosarcoma further.”
PA