There are around 37 trillion cells in a human body, whereas elephants have over a quadrillion. This is that many more opportunities for a cell to mutate into cancer. But elephants don’t get cancer—at least not as much as experts expect. Now scientists have found a gene that may explain why.
About 4.8 percent of elephants die of cancer compared to the 11 to 25 percent of humans, Deborah Netburn writes for The Los Angeles Times. Taking into account that elephants have roughly 100 times more cells than humans, this doesn’t really make sense.
With that many cells, “every baby elephant should be dropping dead of colon cancer at age 3,” says Joshua D. Schiffman, a pediatric oncologist at the Huntsman Cancer Institute at the University of Utah, in Carl Zimmer writes for The New York Times. But they don’t. In the wild, Elephants will live an average of 70 years.
So how do they stave off cancer?
That mechanism just might involve gene called P53, according to two new research papers. The gene is known to surppress tumors and shows up in many species. “When there is DNA damage, it rushes onto the scene and stops your cells from dividing so the DNA can be repaired,” Schiffman tells Netburn for The Los Angeles Times. “It also coordinates cell death or suicide.”
A group from the University of Utah looked at genes from 36 different species including humans and elephants. They discovered that humans have one copy of P53 whereas elephants have at least 20 copies, according to the paper published in The Journal of the American Medical Association.
Scientists have yet to figure out exactly how P53 keeps elephants relatively cancer-free, but the Utah team has a hint. After exposing blood samples to radiation that breaks cellular DNA, they saw that more elephant cells died than the human cells. The extra copies of P53 might be telling defective cells to die rather than risking the rise of cancer, Netburn reports.
The elephant's defense against cancer may be something developed over generations, according to another study currently under review. The small ancestors of elephants had only one copy of P53, like humans. But as their descendants grew larger and got more cells, that changed.
"Whatever’s going on is special to the elephant lineage," Vincent J. Lynch, an evolutionary biologist at the University of Chicago told Zimmer for The New York Times. Hopefully, scientists can learn exactly what is happening and maybe apply it to people someday.