Though we typically think of it as a new affliction attributed to bad habits, bad luck or longevity, a surprising discovery has revealed that the disease existed in human ancestors more than a million years ago.
Scientists have found evidence of cancer in a foot bone and spine from two ancient hominin specimens in South Africa.
The foot fragment is approximately 1.7 million years old and the vertebrae almost 2 million years old.
To put it in perspective, before these finds, the oldest dated possible tumor in a human was only 120,000 years old. That’s a huge difference and vastly expands our recorded timeline of the disease.
What it means
A team of scientists from the the University of the Witwatersrand’s Evolutionary Studies Institute and the South African Centre for Excellence in PalaeoSciencesmade and recorded the discoveries, and they say the bones provide a direct link over millions of years of human evolution.
In fact, you’d never know that the cancer evidence in the foot bone was from prehistoric times, says Edward John Odes of Wits University’s School of Anatomical Sciences.
“We tested this particular bone with a known modern human osteosarcoma specimen, and it looked identical,” he said. “Millions of years old, and you wouldn’t be able to tell it apart.”
Therein lies a tantalizing mystery: In the time since that nameless unlucky soul got bone cancer, massive evolutionary changes have occurred. Things changed. Humans changed. Why didn’t the cancer?
Scientists don’t have the answer. “What we do have is that these types of cancers existed so many years ago, and we are seeing the same thing today.” Odes said. “Normally, in an evolutionary biological situation, you’d see change.”
Up until now, researchers and scientists have held to a tacit assumption that cancer didn’t exist in humans this far back in history. Now that there is proof that it does, the understanding of cancer’s origins and processes will evolve as well.
“This kind of research changes perceptions of cancer,” said Patrick Randolph-Quinney of the University of Central Lancashire. “The takeaway is the notion that cancer is a huge continuous problem in the developed world. Even if we have very healthy, perfect lifestyles we still have the capacity for cancer. It is an inherent part of our evolutionary process.”
How it could benefit cancer research
Many modern cancers have all sorts of variables. “These days, we have cancers that are entirely new, brought on by obesity and diet, alcohol, smoking,” Randolph-Quinney said. “There is a direct causal link.”
The tumors found in the ancient bones were primary osteogenic cancers, which means there weren’t any environmental factors, or variables, to account for their existence. These types of cancers obviously still exist today, so their existence could provide a constant of sorts.
“There has to be something else that’s (causing cancer),” Odes said. “We don’t know know what it is at this stage. We know the capacity for malignancy is ancient. We also know that there are mechanisms that bring these tumors and cancers. The question is, how can we apply these mechanisms to understand the evolution of cancer from ancient times into this modern world?”