Consider the claw. Frequently found on animals around the world, it's one of nature's most versatile tools. Bears use claws for digging as well as defense. An eagle's needle-like talons can pierce the skulls of their prey. Even the ancestors of primates used to wield these impressive appendages, until their claws evolved into nails. So what caused this adaptation? Matthew Borths investigates. [Directed by Augenblick Studios, narrated by Addison Anderson, music by GDM Production Music].
