Elephants Should Be Very Susceptible To Cancer In Theory, Scientists Search For Why They Are Resistant

Why are elephants seemingly so resistant to cancer? In theory, given their size and lifespans, they should be extremely susceptible to cancer, but they aren’t. Dr. Joshua D. Schiffman, from the University of Utah School of Medicine, and his research team believe they are closer to understanding why elephants rarely get cancer than ever before.

In an article published in JAMA, Dr. Schiffman’s team examined data about the causes of death and disease of 36 mammals. Among the mammals analyzed were the African and Asian elephants. The team assessed the animal participant’s genomes, and looked at the activity of a particular type of white blood cell known as peripheral blood lymphocytes among elephants. The cancer death rate for elephants was less than five percent. For humans the rate is up to 25 percent, according to Medical News Today. It turns out elephants are very wealthy in the major tumor-suppressor gene department. Elephants have at least 20 copies of a gene called TP53. We, on the other hand, only get one copy. The scientists believe strongly that elephants managed to evolve their way into protection from cancer, which led to a higher number of copies of this tumor-suppressor gene in their system.

“Compared with other mammalian species, elephants appeared to have a lower-than-expected rate of cancer, potentially related to multiple copies of TP53. Compared with human cells, elephant cells demonstrated increased apoptotic response following DNA damage. These findings, if replicated, could represent an evolutionary-based approach for understanding mechanisms related to cancer suppression.”

Dr. Mel Greaves, from the U.K.’s Institute of Cancer Research, says that the research team’s theory is plausible. Perhaps elephants are protected from cancer due to the extra copies of the TP53 gene, but isn’t sure how the finding will impact humans. Greaves says that human vulnerability to cancer is significantly tied to lifestyle factors that are relatively new in the evolution of our species. Some lifestyle factors are relatively new, with massive new exposure to carcinogens occurring in recent centuries and even recent decades.

“Perhaps the main message from this innovative investigation is to bring into focus the question of why humans appear to be so ill-adapted to cancer, given the average size and life span. The human genome is replete with footprints of positive selection in the not-too-distant historical past. Humans may have acquired, in one particular respect, an extra cancer suppressor gene variant early on in evolutionary history approximately 1.8 million years ago.”

Unfortunately, according to Dr. Greaves, the human lifestyle imparts extremely high cancer risks. If humans didn’t make such unhealthy lifestyle choices, according to Greaves, the cancer-suppressing mechanisms we inherited would have been amply suitable to protect our species from cancer, just like the elephants.

Greaves told BBC News, “In terms of adaptive mechanisms against cancer we have the same as a chimp, but we get a lot more cancer than a chimp. I think the answer is humans are completely unique as a species in having very rapid social evolution in a short period of time.”

Schiffman and his team do know how they plan to apply the findings to humans. The team wants to use this information learned from elephants and either create a drug that mimics the mechanisms of the TP53 genes or actually insert extra TP53 genes into precancerous cells.

“Evolution has had 55 million years to figure this out,” Schiffman said, referencing the development of the needed amount of TP53 genes, according to the LA Times. “We want to learn how to take advantage of that.”

[Photo via Pixabay]