From Wikipedia: In the second century AD the Emperor Hadrian, according to Dion Cassius, was the first of all the Caesars to grow a beard; Plutarch says that he did it to hide scars on his face. This was a period in Rome of widespread imitation of Greek culture, and many other men grew beards in imitation of Hadrian and the Greek fashion. Until the time of Constantine the Great the emperors appear in busts and coins with beards; but Constantine and his successors until the reign of Phocas, with the exception of Julian the Apostate, are represented as beardless.
Hadrian
Marcus Aurelius
**The author skipped a big deal in Roman history—the Age of the Beard.**
Well, that’s because it’s a history of shaving, not a history of facial hair.