Exactly how they are related to this group is a matter of debate, and illustrates nicely the richness of Darwin's legacy. There are fossil whales, and since the Sixties, palaeontologists have carefully reconstructed a hypothetical route from terrestrial mammals to modern whales via an extinct group, the mesonychians. The story has changed with the application of DNA sequencing to the business of sorting out who is related to whom in the natural world. Whales are derived from a specific group within the Artiodactyls, the hippopotamuses. Darwin, himself a genuine polymath, competent in geology, palaeontology, systematics, ecology, animal behaviour and developmental biology, would be proud.
Whales have a further major claim to evolutionary fame.
Those hind legs, vestiges of a genealogically distant four-limbed ancestor, have atrophied to such an extent that they merely put in a brief appearance in the whale's embryonic development as cartilagenous stubs that are rapidly reabsorbed. That they appear at all, however, is testimony to the inertia inherent in the evolutionary process. A more striking instance of this came to light off Vancouver Island in 1919 when whalers killed a female humpback whale with a pair of bizarre protrusions on either side of its tail. These were four feet long and unmistakably those 'lost' hind limbs. Jones's Darwinian borrowings are not limited to the title of his book.