The idea comes down to a protein called p53, which helps prevent DNA damage in cells — including damage that could turn a normal cell into a cancerous cell.
Through a quirk of evolutionary history, however, elephant testicles are located inside their bodies. As multi-ton, dark gray animals walking around in the sun, their testicles have the potential to get really hot — and therefore the elephants may have trouble making viable sperm. But if they had more copy-editing proteins, the theory goes, that hot sperm could be protected from damage..
It's possible that multiple copies of the p53 gene evolved to protect elephant sperm from hot temperatures. But it's also possible that those multiple copies evolved because elephants are big animals so are potentially more susceptible to cancer, Lynch said. It could also be both things at once.