Biology
What does our tailbone tell us about evolution?
Quick fact
The coccyx (tailbone) is the fused vestige of a tail that our mammalian ancestors used for balance, movement, and communication—now it's an attachment point for pelvic muscles and tendons.
Why this is interesting
You have a tail—it's just shrunk to a small, fused bone at the bottom of your spine, a relic from our tree-dwelling ancestors that lost its purpose but not its presence.