An excerpt from a piece on razors and the like at Tech Central Station:

The mysterious Etruscans have left us fine razors of bronze. Somehow, their inheritors, the Romans, retreated to iron, which rusted away, leaving few archaeological examples.

The ancient Greeks wore beards until they were conquered by Alexander the Great (356 to 323 B.C.), who was a fanatic about being clean shaven and established the smooth-cheeked ideal.

The Romans, likewise, affected beards until around the late 2nd century B.C., when the Greek ideal began to catch on. Scipio Aemilianus, the adopted grandson of the great Scipio Africanus, looked forward to his daily shave (at the hands of a tonsor) and seems to have done much to establish the vogue.

But it was Julius Caesar (100 to 44 B.C.) who really set the standard. He insisted on being clean-shaven at all times, even late in the day. Jerome Carcopino, in his wonderful book, Daily Life in Ancient Rome, writes that Caesar made shaving such a fixture that "by the end of the first century B.C. nothing but the gravest or most painful crisis would have induced the great men of the day to omit a formality which had become for them a state duty."

And, Carcopino notes, ordinary Romans "would have thought themselves unworthy of their imperial masters if they had not followed suit." Those who could not afford a specially-trained in-house slave to shave them, repaired to the public square, where barbers set up shop, some becoming so famous that they were extolled by Roman poets.

Shaving became almost a religious rite -- a passage into manhood for Roman boys, who would have the hairs from their first shave deposited in an ornate receptacle with the date of the great event duly recorded.