Chapter 1
“All the Hugest, and
Fiercest, and Strangest Forms Have Recently
Disappeared”
Exploring the eastern coast of Argentina in the early 1830s, in the vicinity of what is today the Puerto Belgrano Naval Base, the young Charles Darwin examined the bones of the elephant-sized ground-slothMegatherium and at least nine other extinct species he described as “gigantic quadrupeds.”
“It is impossible,” he wrote, “to reflect on the changed state of the American continent without the deepest astonishment. Formerly it must have swarmed with great monsters: now we find mere pigmies [sic], compared with the antecedent allied races.” Darwin was astounded, too, by howrecently these “great monsters” had become extinct: their bones were embedded, in some cases, in deposits containing the shells of modern, still-existing mollusk species. It was a state of affairs that cried out for an explanation. “Did man,” Darwin wondered, “after his first inroad into South America, destroy, as has been suggested, the unwieldy Megatherium and the other Edentata?”
The mystery deepened when his friend and mentor Charles Lyell informed him that North America had also lost a suite of “great monsters” (which included mammoths among many other large mammal, reptile, and bird species). “The mind at first is irresistibly hurried,” Darwin wrote, “into the belief of some great catastrophe; but thus to destroy animals…in Southern Patagonia, in Brazil, on the Cordillera of Peru, in North America up to Behring’s Straits, we must shake the entire framework of the globe.”
Darwin was to learn, in the years that followed his return from theBeagle voyage, that this “earth-shaking” wave of large-animal extinctions had engulfed not only the Americas, but also Eurasia (which had seen the relatively recent loss of mammoths, mastodonts, woolly rhinoceroses, giant deer and many other species) and Australia (where a rhino-sized marsupial herbivore, a marsupial “lion” approaching the “real” or placental lion in size, and a great many other big marsupials, reptiles and birds also disappeared near the end of the Pleistocene Epoch).
Alfred Russel Wallace, the co-discoverer with Darwin of evolution by natural selection, was equally puzzled by this recent disappearance of so many of the earth’s big land-animals, writing, in 1876, that
…we live in a zoologically impoverished world, from which all the hugest, and fiercest, and strangest forms have recently disappeared; and it is, no doubt, a much better world for us now that they have gone. Yet it is a marvelous fact, and one that has hardly been sufficiently dwelt upon, this sudden dying out of so many large Mammalia, not in one place, but over half the land surface of the globe.
At first, Wallace thought that the “sudden dying out” of these big beasts had been caused by “the great and recent physical change known as the ‘Glacial Epoch’,” but, writing in 1911, his eighty-eighth year, he changed his mind:
Looking at the whole subject again, with the much larger body of facts at our command, I am convin