In the fossil-rich region of South Africa known as the Cradle of Humankind, scientists have discovered the earliest known case of one of the world's most deadly diseases.
A recent study has changed the conventional opinion about cancer was that it is a relatively recent phenomenon cause by the stresses of modern life. Dietary changes, behavioral changes and man-made changes to our environment have subjected humans to toxins that contribute to cancers.
‘Discovery of a 1.7 million year old cancerous foot bone and a 2 million year old vertebrae ravaged by tumors, show that cancer is not a modern disease. It will help medical researchers understand the evolution mechanism of cancer and its behavior.’
Researchers led by scientists from the University of the Witwatersrand's Evolutionary Studies Institute and the South African Centre for Excellence in PalaeoSciences announced in two papers the discovery of the most ancient evidence for cancer and bony tumours yet described in the human fossil record.
Paleontologists found a benign tumor in a specimen from a 12 or 13 year old boy that dates back almost 1.7 million years old. They also found a malignant tumor on a little toe bone of a left foot from the site of Swartkrans cave in Johannesburg, that 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.
Using a method called micro-CT imaging, the research team studied detailed 2-D and 3-D images of the fossil's interior. Images recorded the density differences within the bone and generated views of the fragment from all directions.
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. It was liable to spread to other parts of the body and could have been life-threatening. The cancer had taken over the inside of the subject's little toe and sprouted a bone spur on the side of the foot. Researchers said the growth most likely would have struck the ground as the person walked, a very painful experience that also could have made the subject, who is identified without a gender, very vulnerable to predation.
The benign tumor in the 12-year-old boy was found in the sixth thoracic vertebra in the middle of the back. It was osteoidosteoma, or a small bone tumor that compromised part of the vertebra. The tumor was benign, researchers said, meaning it would not spread or become life-threatening. But it would be uncomfortable with a small bone sticking out of the middle of your back and it left the boy most likely limited in the physical activity and made him vulnerable to predators.
In an accompanying paper appearing in the same journal, a collaborating team of scientists identify 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.
Lead author of the tumour paper and co-author of the cancer paper, Dr Patrick Randolph-Quinney suggested "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."
Edward Odes, lead author of the cancer paper noted, "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."
"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 Dr Bernhard Zipfel, a Wits scientist. He added that t would have been painful.
Lee Berger, an author on both papers, added that there has not only been an assumption that these sorts of cancers and tumours are diseases of modernity, which these fossils clearly demonstrate they are not, but that modern humans exhibit them as a consequence of living longer, yet this rare tumour is found in a young child.
The study is published in South African Journal of Science
The earliest discussion of cancer, came from Egyptian physician Imhotep, who described in his writings a bulging at the breast that did not respond to any known remedies.
Things go wrong inside our bodies, the study says, that are unrelated to stresses brought on by society, like pollution and smoking. Even millions of years ago, they sometimes resulted in tumors or growths that may or may not have been cancerous.
The greatest predictor of cancer, the study argues, even in our ancestors, is longevity. The longer we live, the more chances something in our bodies goes wrong, the more chances that something is a tumor. The incidence of cancer has increased over time because our habits have changed. There are more opportunities for things to go wrong.
Randolph-Quinney said the research team wants to use its findings to understand how cancers evolved over time and to master the ancient mechanics of unregulated cell growth, both benign and malignant. By perhaps finding those answers, medical researchers might be a step closer to understanding cancer's behavior.