Today, we know cetaceans (whales, dolphins, and porpoises) descended from terrestrial mammals called artiodactyls, a group including even-toed ungulates like pigs, giraffes, and hippos.

We might think of them as smooth, two-flippered ocean swimmers that struggle to even survive the Thames, but whales originated more than 50 million years ago from artiodactyls – land-dwelling, hooved mammals.

We might think of them as smooth, two-flippered ocean swimmers that struggle to even survive the Thames, but whales originated more than 50m years ago from artiodactyls – land-dwelling, hooved mammals.

In the 1950s immunologists had discovered characteristics in whale blood that suggested a descent from artiodactyls, the mammalian order that includes pigs, deer, camels, and other even-toed ungulates.