Elephants have evolved extra copies of a gene that fights tumour cells, according to two independent studies1, 2 — offering an explanation for why the animals so rarely develop cancer.
Why elephants do not get cancer is a famous conundrum that was posed — in a different form — by epidemiologist Richard Peto of the University of Oxford, UK, in the 1970s3. Peto noted that, in general, there is little relationship between cancer rates and the body size or age of animals. That is surprising: the cells of large-bodied or older animals should have divided many more times than those of smaller or younger ones, so should possess more random mutations predisposing them to cancer. Peto speculated that there might be an intrinsic biological mechanism that protects cells from cancer as they age and expand.
