Body & HealthFact
A 28-year-old corrected some 300 medical errors in 1543.
Andreas Vesalius published "De humani corporis fabrica" in 1543, seven books with more than 250 illustrations. He rectified roughly 300 of Galen's errors – Galen had mostly dissected animals – including the ideas that the lower jaw consists of two bones and that men have fewer ribs than women.
Useful: Authority is no substitute for looking: Galen stood unchallenged for 1,300 years because nobody checked.
Source: en.wikipedia.org