The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth's Past Mass Extinctions

by Peter Brannen

After millions of years of relative stability, even through countless punishing climate swings, a strange wave of extinctions suddenly swept across the planet, eerily shadowing the heroic migrations of the recently evolved African primate species Homo sapiens. Starting only a few tens of thousands of years ago, the extinctions jumped from continent to continent, then to remote islands, and they continue unchecked to the modern day. The idea of man-made extinctions evokes images of gasoline-chugging chainsaws melting through old-growth timber, or industrial fishing trawlers sterilizing the seabed with rusty submarine plowshares, but in fact, humanity’s gain has been biodiversity’s loss since birth. Sometime between 40,000 and 50,000 years ago, Australia lost its marsupial lions and its giant kangaroos, which were far larger (and slower) than those now living. It lost its diprotodons, giant lumbering herbivores the size of rhinoceroses—the largest marsupials to ever live. It lost its giant flightless birds, more than 6 feet tall. It lost a giant python, two species of terrestrial crocodiles, and an enormous monitor lizard called megalania, which, stretching some 15 feet, looked as though it got lost en route to the Triassic. It lost absolutely every animal on land weighing more than 100 kilograms (220 pounds). The wave of extinction struck, not during any unusual climate perturbation or asteroid impact, but at about the same time that the first humans arrived in Australia.