Even 2 Million Years Ago, Cancer Plagued Human Ancestors

Pam Harrison

August 02, 2016

The earliest evidence of both a malignant and a benign tumor has been found in human fossils from two separate caves in South Africa. The fossils date back almost 2 million years, showing that cancer is not a disease caused by our modern lifestyles, as some have suggested.

The findings are described in two articles published online July 28 in the South African Journal of Science.

In one article, scientists describe a malignant osteosarcoma in a 1.7-million-year-old metatarsal found in the Swartkrans Cave in the Cradle of Humankind, an anthropological site in South Africa.

"It has generally been assumed that premodern incidence of neoplastic disease of any kind is rare and limited to benign conditions, but new fossil evidence suggested otherwise," writes lead author Edward Odes, a doctoral candidate at the University of the Witwatersrand, Johannesburg, South Africa, and colleagues.

Volume-rendered image of the external morphology of the foot bone, showing the extent of expansion of osteosarcoma beyond the surface of the bone.

 

"We here present the earliest identifiable case of malignant neoplastic disease from an early human ancestor dated to 1.8–1.6 million years old,” they write, adding, "The diagnosis has been made possible only by advances in 3D imaging methods as diagnostic aids."

In the second article, the team provides the earliest evidence for benign neoplastic disease affecting the sixth thoracic vertebra in a male child between the ages of 12 and 13 years.

The vertebral lesion was identified in an extinct hominin, Australopithecus sediba, from Malapa, South Africa, dated to 1.98 million years ago.

"Tumours of any kind are rare in archaeological populations and are all but unknown in the hominin record, highlighting the importance of this discovery," write the authors, led by Patrick Randolph-Quinney, PhD, also from the University of the Witwatersrand, who is senior lecturer in biological and forensic anthropology at the University of Central Lancashire in the United Kingdom.

"The presence of this disease at Malapa predates the earliest evidence of malignant neoplasia in the hominin fossil record by perhaps 200,000 years," the team notes.

Sixth thoracic vertebra of juvenile Australopithecus sediba (Malapa Hominin 1) showing partially transparent image volume with the segmented boundaries of the lesion rendered solid pink.

 

Advanced Imaging

The exact species in which the malignant osteosarcoma was found is not known, but the metatarsal was clearly from a hominin or bipedal human relative.

Using advanced imaging, researchers were able to get an "absolutely crisp image" of the bone specimen, which enabled them to diagnose malignant sarcoma.

"We looked into the medullary cavity, and it was completely filled with new bone formation, osteoblastic bone formation, and this expansive new bone formation in the medullary cavity led me to say, 'Hang on a second, this is abnormal,' " Edward Odes said in an official YouTube video from the University of Witwatersand.

Dr Randolph-Quinney concurred, adding that the fact that researchers could identify very aggressive, irregular bone growth on the surface of the metatarsal ― aggressive new growth that had obviously spread into the medullary cavity ― clinched the diagnosis of an aggressive osteosarcoma, which likely would have had very painful, if not fatal, consequences.

"Recent studies on Egyptian mummies failed to identify traces of cancer, leading some researchers to suggest that cancer wasn't present in our premodern world," Odes said in the same video.

"But this study falsified that," he added.

"The expression of malignant osteosarcoma in the Swartkrans...specimen indicates that whilst the explosion of malignancy incidence is clearly correlated with the hazards of the modern world and increased life expectancy, primary bone tumours evidently occurred throughout history," Odes and colleagues conclude in their article.

Vertebral Neoplasm

The vertebral lesion that Dr Randolph-Quinney and colleagues describe in the extinct hominin Australopithecus sediba from Malapa was a penetrating lytic lesion that extended ventrally into the lamina for much of its length.

The neoplastic lesion identified in the vertebral fossil was chronic and was still active at the time of the child's death, the researchers note.

Morphologic and pathologic analyses suggested that the lesion was either an osteoid osteoma or, a close second, an osteoblastoma. Both are benign, bone-forming tumors, are osteoblastic in nature, and are most likely to occur in male juveniles and adolescents.

"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," Dr Randolph-Quinney said in a statement.

"This in fact is the first evidence of such a disease in a young individual in the whole of the fossil human record," he added.

Fossil Remains

Asked to comment on the evidence for neoplastic disease in the young, Ted Gansler, MD, MPH, strategic director, pathology research, American Cancer Society, told Medscape Medical News that many types of malignant and benign tumors in humans can also occur in other species of animals, and some have been found in fossil remains of extinct species as well.

"The current article describing a fossilized vertebra containing a bone tumor in an adolescent Australopithecus sediba who lived nearly 2 million years ago would make this the oldest specimen of a neoplasm of any hominin species," Dr Gansler reaffirmed.

Dr Gansler also pointed out that osteoid osteoma is one of the most common benign bone neoplasms to occur in modern humans and is typically seen in adolescents and young adults. Osteoid osteomas are not associated with any "modern" carcinogenic risk factors, such as smoking and obesity, he pointed out.

"So in fossilized bones, from an extremely ancient population with a very short life expectancy, I'd expect osteoid osteomas to be a lot more common than, for example, metastatic carcinoma," Dr Gansler added.

Indeed, Dr Randolph-Quinney postulated that it is likely that neoplastic disease was as prevalent in ancient hominin populations as it is in modern individuals but that it left little fossil trace, likely because so few individuals have been recovered from the hominin record.

The authors of the two articles have disclosed no relevant financial relationships.

S Afr J Sci. Published online July 28, 2016. Article one, abstract; article 2, abstract

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