The Dire Wolf Is Back

Extinction is a part of nature. Of the five billion species that have existed on Earth, 99.9 per cent have vanished. The Triassic-Jurassic extinction, two hundred million years ago, finished off the crocodile-like phytosaur. Sixty-six million years ago, the end-Cretaceous extinction eliminated the Tyrannosaurus rex and the velociraptor; rapid climate change from an asteroid impact was the likely cause. The Neanderthals disappeared some forty thousand years ago. One day--whether from climate change, another asteroid, nuclear war, or something we can't yet imagine--humans will probably be wiped out, too.