The Sixth Extinction: An Unnatural History

by Elizabeth Kolbert

A recent study of visitors to Antarctica found that in a single summer season, tourists and researchers brought with them more than seventy thousand seeds from other continents. Already one plant species, Poa annua, a grass from Europe, has established itself on Antarctica; since Antarctica has only two native vascular plant species, this means that a third of its vascular plants are now invaders.

The first pulse, about forty thousand years ago, took out Australia’s giants. A second pulse hit North America and South America some twenty-five thousand years later. Madagascar’s giant lemurs, pygmy hippos, and elephant birds survived all the way into the Middle Ages. New Zealand’s moas made it as far as the Renaissance.