IN 1977 RICHARD PETO, an epidemiologist at Oxford University, observed a contradiction. Cancer begins as a mutation in a single cell. Organisms with more cells should therefore have a higher risk of developing it. Elephants, which have 100 times as many cells as human beings do, should swarm with malignancies. Whales, with ten times more again, should be barnacled with tumours. In fact, the planet’s behemoths are blessed with extremely low rates of cancer. Titanic bodies and tumour resistance have evolved in tandem. The secret of suppressing cancer may therefore be hidden in the genes of giants.
Inspired by Peto’s paradox, as this contradiction has come to be known, researchers are exploring rates of cancer and resistance to cancer in thousands of animal species, with an emphasis on heavyweights. Their hope is to translate the animals’ cancer-fighting talents into treatments for people.