Scientists have spent decades thinking why elephants and other large mammals do not suffer from cancer in comparison to smaller mammals. A new research has found the reason and that is a gene called TP53, also known as guardian of the genome.

Researchers have unveiled that African elephants have 20 copies of the gene TP53. This gene is quite vital as it has the ability to create a protein that suppresses tumors. On the other hand, humans have just one copy of TP53.

Study’s senior author Dr. Joshua Schiffman, a pediatric oncologist at the Huntsman Cancer Institute in Salt Lake City, said this crucial gene keeps cells protected from cancer through two ways. Firstly, when there is DNA damage it reaches the spot and stops the cells from dividing, so that DNA gets needed time to repair. Secondly, it coordinates cell death.

In order to fight off cancer, humans who inherit one allele of TP53 from each of their parents should be functional. If one allele is defective, then cancer is certain to develop sooner or later.

Schiffman teamed up with Carlo Maley of Arizona State University and they assessed the Elephant Encyclopedia, which had information about elephants living in captivity across the globe. The database had details of 644 elephants.

It was found that just 3.11% of those elephants had it when they lost their lives. They also found 20 copies of TP53 in African elephants in which one was original and 19 were formed over time.

“It’s like the elephant said, ‘It is so important that we don’t get cancer that we can’t risk trying to repair our broken DNA and accidentally let a mutation slip by,’” Schiffman said. “It makes tremendous sense — the best way to prevent cancer in a cell is to eliminate entirely.”

“All this leads us to conclude that these extra copies of TP53 may have evolved to protect elephants from cancer,” Schiffman said. “And I say ‘may’ because the only way to know for sure is to build an elephant that has no copies of TP53” and see whether it’s more vulnerable to cancer. Although researchers often breed mice that lack working copies of certain genes, “that’s not going to happen” with elephants, he said.