UNIVERSITY OF CALIFORNIA PRESS, NOVEMBER 2014Scientists ever since Aristotle have known that whales and dolphins were mammals, but for most of human history, the general public was not aware of this scientific fact or simply did not agree. In Moby Dick, Ishmael opines thusly: “Be it known that, waiving all argument, I take the good old fashioned ground that the whale is a fish, and call upon holy Jonah to back me.” Even Charles Darwin struggled with the concept. In the first edition of On the Origin of Species, he suggested that whales might be derived from bears that filtered insects out of the water, but after being ridiculed for that idea, he eliminated the statement from later editions.
For centuries, it was difficult to conceive of a whale ancestor that combined features of its land-mammal ancestors and its aquatic descendants. And the fossil record was little help; nearly all fossil whales were very similar to modern whales. Because the scant fossil evidence failed to suggest terrestrial ancestry, whale evolution became a pet subject of creationists.
The past two decades have changed all that, and whale evolution now is one of the best examples of macroevolution documented in the fossil record. In The Walking Whales, I revisit the evolutionary origin of whales, from little Indohyus, the tiny deer-like critter that roamed the forest floor in the middle Eocene, diving into the water to avoid predators, to Basilosaurus, the first fully aquatic leviathan of the ...
