How Do We Know These Are Human Fossils?

They all have two features that distinguish humans from other apes, living and extinct.

• Both males and females have small canine teeth.
• The hole where the spinal cord enters the braincase is located toward the center—a clue to walking upright.

Human
Small canines in males
Spinal cord enters braincase farther forward

Chimpanzee
Large canines in males
Spinal cord enters braincase farther back