Cancer is not a modern disease, scientists have confirmed. In the Cradle of Humankind in South Africa, a region known for its fossils, scientists have unearthed the earliest case of the dreaded disease, National Geographic reports.
The researchers used 3D imaging to locate an aggressive type of cancer called osteosarcoma in the foot bone of a human who died in Swartkrans Cave some 1.6 to 1.8 million years ago.
This discovery suggests that while modern factors have raised cancer incidences in the past century or so, the triggers for it are entrenched within the history of human evolutionary.
Edward Odes of the University of Witwatersrand, co-author on the study, says,
You can opt for the paleo diet, you can have as clean a living environment as you want, but the capacity for these diseases is ancient, and it’s within us regardless of what you do to yourselves.
The origin of cancer has been an ongoing debate brought on by the lack of historical evidence. The earliest likely reference to cancer is credited to the famous Egyptian doctor Imhotep, who lived around 2600 B.C. He documented a condition characterized by a “bulging mass in the breast” that proved resistant to any known treatments at the time.
However, other ancient texts have no information on the disease, and anatomically correct descriptions of malignant tumors did not surface until the late 18th century.
One possible reason why cancer is not present until later in historical records is because it most commonly afflicts people 65 years old and older, meaning only a few people lived long enough for cancer to gain attention.
Oncologist Siddharta Mukherjee says in his book, The Emperor of All Maladies, “Civilization did not cause cancer. But by extending human life spans, civilization unveiled it.”
Prehistoric evidence of cancer has likewise been missing in fossil records, which only preserves a tiny fraction of the bones of humans who lived at any given time. Some scientists have gone as far as to study mummies, where soft tissue could be studied.
In 1990, for example, autopsies conducted on a thousand-year-old mummies in Peru revealed that at least one woman in her 30s had a malignant tumor in her upper-left arm. The tumor was so large that it would have burst through her skin had she lived.
Mummification goes back a few thousand years, but fossil records go back millions. Now, Odes and his fellow scientists are confident that the hominin bone they studied, found at the Swartkrans site close to Johannesburg, has the oldest known case of malignant cancer.
The team used micro-CT imaging to study detailed 2D and 3D images of the fossil’s interior. The images documented the difference in density within the bone and produced views of the bone from all angles.
An irregular growth pattern of bone tissue, including a distinctive, cauliflower-like shape, led the scientists to diagnose osteosarcoma, which afflicts children and young adults today.
Odes says that they compared the fossil images and a modern biopsy, saying, “It was bingo.”
The bone, a fragment of a toe from the left foot, is the only fossil from the skeleton that was found. There was too little information to determine which hominin species it belonged to, what age it was, or if the cancer caused death.
What scientists can tell is that the cancer would have been very painful, making walking or running difficult.
In addition to the toe fossil, Odes and his colleagues also studied an older fossil, this time with a benign tumor.
In a separate study, the team describes a vertebrae growth from a young skeleton dating back 1.98 million years ago, called Australopithecus sediba. The fossil was excavated by National Geographic expert Lee Berger in Malapa, a few miles away from Swartkrans. Before this, the oldest recorded benign tumor was in a 120,000-year-old Neanderthal, found in Croatia.
The benign tumor in Malapa is further evidence that malignant cancer existed among the human race’s earliest ancestors.
“A tumor is new growth of bone or tissue, where you have a sliding scale from benign to malignant,” paleoanthropologist Patrick Randolph-Quinney, one of the scientists on the study, says. “On the benign side, there are mechanisms that keep these tumors in check, so they are self-limiting, or they reach a certain size and they basically stay there. Whereas cancer is the extension of that growth process without the control mechanisms.”
The researchers say their results are a significant reminder that cancer is a moving target. Evolution has bestowed modern humans with the genes that contain the ability to trigger cancer, but it manifests when there are changes in the environment.
For example, stomach cancer proliferated more until the late 19th century, likely because of carcinogens found in food preservatives. Now, colon cancer is a major cause of concern, possibly because of the increasing presence of saturated fats in food.
Odes says, “The modern external environment is doing things to our historical internal environment that we’ve never encountered before in our evolutionary history.”
The discovery was published in the South African Journal of Science.
