If you have teenagers — or were once a teenager yourself — you've probably experienced this: Your kid's jeans fit perfectly in September, but by December they're showing ankle. The adolescent growth spurt can feel astonishingly fast, with some teens growing 4 to 5 inches (10 to 13 centimeters) in a single year. But is this really the fastest period of human growth?
Surprisingly, no: The teenage growth spurt is only the second fastest that humans can grow.
