You've got to 'hand' it to Homo Erectus.

• Position: Human Evolution

Humans have a distinctive hand anatomy that allows them to make and use tools. Apes and other nonhuman primates do not have these features in their hands, and the point in time at which they first appeared in human evolution is unknown. Now, a University of Missouri, Columbia, researcher and her international team of colleagues have found a hand bone from a human ancestor who roamed the Earth in East Africa approximately 1,420,000 years ago. They suspect the bone belonged to the early human species, Homo erectus. The discovery is the earliest evidence of a modern human-like hand, indicating that this anatomical feature existed more than 500,000 years earlier than previously known.

"This bone is the third metacarpal in the hand, which connects to the middle finger. It was discovered at the 'Kaitio' site in West Turkana, Kenya," says Carol Ward, professor of pathology and anatomical sciences. "What makes this bone so distinct is the presence of a styloid process, or projection of bone, at the end that connects to the wrist. Until now, this styloid process has been found only in us--the Neanderthals--and other archaic humans."

The styloid process helps the hand bone lock into the wrist bones, allowing for greater amounts of pressure to be applied to the wrist and hand from a grasping thumb and fingers. Ward and her colleagues note that a lack of the styloid process created...