Scientists suggest that cancer may not be a consequence of modern lifestyles.
Johannesburg: Scientists have discovered the world's oldest evidence for cancer and bony tumours in human ancestor fossils found in South Africa, dating back to nearly two million years, suggesting that these deadly diseases may not be a consequence of modern lifestyles.
The discovery of a foot bone dated to about 1.7 million years ago from Swartkrans in South African, with definitive evidence of malignant cancer, pushes the oldest date for this disease back from recent times into deep prehistory.
Although the exact species to which the foot bone belongs is unknown, it is clearly that of a hominin, or bipedal human relative, according to researchers from the University of the Witwatersrand and the South African Centre for Excellence in PalaeoSciences.
Scientists also identified the oldest tumour ever found in the human fossil record, a benign neoplasm found in the vertebrae of the well-known Australopithecus sediba child, Karabo from the site of Malapa, and dated to almost two million years in age.
The oldest previously demonstrated possible hominin tumour was found in the rib of a Neanderthal and dated to around 120,000 years old.
"Modern medicine tends to assume that cancers and tumours in humans are diseases caused by modern lifestyles and environments," said Edward Odes, doctoral candidate at University of the Witwatersrand.
"Our studies show the origins of these diseases occurred in our ancient relatives millions of years before modern industrial societies existed," Mr Odes said.
The cancer in a foot bone, a metatarsal, was identified as an osteosarcoma, an aggressive form of cancer which usually affects younger individuals in modern humans, and, if untreated typically results in early death.
"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," said Bernhard Zipfel, a scientist at University of the Witwatersrand.
"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," said Patrick Randolph-Quinney from the University of Central Lancashire in the UK.
"This, in fact, is the first evidence of such a disease in a young individual in the whole of the fossil human record," he said.
"Not only has there been an assumption that these sorts of cancers and tumours are diseases of modernity, which these fossils clearly demonstrate they are not, but that we as modern humans exhibit them as a consequence of living longer, yet this rare tumour is found in a young child," said Lee Berger, from University of the Witwatersrand.
The research was published in the South African Journal of Science.