Seventy years ago, importing the cane toad to control insects in the sugar-cane fields of Australia seemed like a great idea. The strategy backfired however because the toads are not only toxic, they've also become highly invasive, expanding their range about six miles per year between the 1940s and the 1960s.

Today, cane toads are expanding more than 30 miles annually, and weigh up to 4.4 pounds, crushing native species in their path. How are they able to move so much more rapidly than before? Scientists have discovered that the cane toads have mutated and evolved longer hind legs— much better for moving quickly and staking out new territory.