Researchers Diagnose Earliest Known Cancer on 1.7-Million-Year-Old Hominin Fossil
Scientists have identified a particularly lethal form of cancer on the fossilized toe bone of an early human relative who lived about 1.7 million years ago in South Africa.
The tumor is the oldest known instance of malignant neoplastic disease (cancer) identified in a hominin, say the authors of a paper in the South African Journal of Science.
“The reported incidence of neoplastic disease in the extinct human lineage is rare. Only a few confirmed cases of Middle or Later Pleistocene dates (780,000 to 120,000 years old) have been reported,” wrote Edward J. Odes and co-authors in their article.
They analyzed the growth on the toe fossil, found in Swartkrans Cave in a region known as the Cradle of Humankind, using sophisticated 3D imaging to reach the diagnosis of malignant osteoscarcoma, a type of bone cancer. The bones date to between 1.8 and 1.6 million years ago.
The authors say that since 1999, cancer has been the leading cause of death in U.S. residents under age 85, overtaking heart disease. It is the leading cause of death in all industrialized countries and the secondary cause in developing nations.
The fact that people are living longer contributes to the higher frequency of cancer in modern humans. Cancer usually strikes people over age 65, and a majority of humans didn’t start living past that age until relatively recently in history.
But, the authors say, the triggers for the disease apparently lie way further back in the prehistory of life on this planet. A number of what the authors call “oncogenes” are “particularly archaic” in very primitive animals.
“The fact that malignancy has great antiquity is demonstrated from the fossil record,” they wrote, referring to tumors found on dinosaurs and other animals that lived millions of years ago. But they say it is rare among prehistoric humans.
Cancers seem to be found only in complex vertebrate animals. A jawless hagfish, a type of lamprey, is the only simple vertebrate ever to have been found with a malignant tumor. “This is a very important case for the comparative pathology of malignancy, because lampreys are among the simplest living vertebrates,” the authors wrote.
X-ray of a cat with lung cancer (Wikimedia Commons photo/Xxxantilllxxx)
While evidence for cancers in humans is rare in the fossil, archaeological and historical literature, it is not unknown they wrote. Previously, the oldest tumor was on the spine of an Australopithecus sediba fossil dating back about 1.98 million years, also from South Africa. However, that early human’s tumor was benign. Other researchers diagnosed a Neanderthal rib from Krapina, Croatia, dating back about 120,000 years with a cancerous tumor.
This female Australopithecus sediba model by John Gurche shows how such early human relatives may have looked. Credit: Brett Stirton
The article says research on Egyptian mummies “has suggested to some scholars that malignancy was almost absent in pre-modern human populations. For example, Gray reported no radiological confirmation of malignant neoplasia among 193 examined Egyptian mummies. However, we view this assertion as tautological, because the samples on which the claim is based are not representative of the bulk of the human species living in antiquity; they represent only a small fraction of all humans living at that time. From the global historical sample available to us for study, malignancy does exist, albeit rarely – and a subset of those cases include osteosarcoma. Probable pre-modern cases are reported from Hawaii, the Czech Republic, and the Peruvian Andes.”
In modern humans, malignant cancers are thought to be caused by more advanced age and environmental factors, including exposure to chemicals. Smoking, drinking, sunbathing and obesity can all cause various types of cancers, as can pesticides and industrial chemicals.
Featured image: A view of the fossilized, 1.7-million-year-old hominin toe bone upon which the cancerous tumor was diagnosed. (Photograph by Patrick Randolph-Quinney, UCLAN)
By Mark Miller