Earliest hominin cancer

Malignant tumour found in 1.7m year old metatarsal

Cancer is the primary cause of death in industrialised countries and the second most common cause of death in the developing world. The condition not known to occur in non-chordates and is largely confined to the higher vertebrates. It is extremely ancient, with purported cases of neoplasm found in fossil fish from the Upper Devonian. It may therefore be assumed that hominins have always been afflicted by cancer, but evidence for malignant tumours is rare in the fossil record. The earliest example affecting an archaic human is a case of fibrous dysplasia from a Neanderthal rib dated to 120,000 years ago from the site of Krapina in northern Croatia.

The earliest evidence yet described for malignant bony tumours in the hominin fossil record has recently been announced by a South African team. They found definite evidence for a malignant tumour in a hominin fossil designated SK 7923: a left fifth metatarsal from the cave site of Swartkrans in the Cradle of Humankind, South Africa, dating to between 1.6 and 1.8 million years old. The exact species has not been determined, but the site has previously yielded fossils of Paranthropus robustus and Homo erectus.

The tumour was identified as an osteosarcoma, a rare primary bone cancer which in modern humans usually affects younger people. Early diagnosis and treatment can effect survival rates of 60 to 80 percent, although until the 1960s the outlook was very poor. It was not clear how old SK 7923 was at death, or whether the cancer was the cause of death, but the cancer would have affected their ability to walk and run – which by itself could have ultimately proved fatal.

The same team also reported a benign bone tumour affecting the juvenile Australopithecus sediba MH 1 from Malapa, dating to 1.98 million years ago.

It is often assumed that both malignant and benign tumours in humans are the result of modern lifestyles and environments, but these results show that they occurred in our ancient relatives millions of years before modern industrial societies arose.

References:

Odes, E. et al., Earliest hominin cancer: 1.7-million-yearold osteosarcoma from Swartkrans Cave, South Africa. South African Journal of Science 112 (7/8) (2016).

Randolph-Quinney, P. et al., Osteogenic tumour in Australopithecus sediba: Earliest hominin evidence for neoplastic disease. South African Journal of Science 112 (7/8) (2016).

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