Coming in many shapes, sizes and colors, the beard is a prominent feature on most men who do not shave (and the occasional woman - though let's not go there). Today, pogonotrophy is normally accepted in society; but in the past, growing a beard could cause quite a few problems. Sprouting your manly facial hair could get you taxed, be a sign of rebellion against the church - or could even get you killed.
At the least, removal of facial hair can be painful. Archaeologists have found evidence that men started to shave off their beards as early as 100,000 BC. However, the the first razors discovered by archaeologists date back to 30,000 BC, and were made of flint. Thus, before then shaving was a painful ordeal. One who wanted a bare face would use two sea shells to grip their hair, then pull; a method which sounds even more distressing than getting a bikini wax.
Beards were in the vogue in Greek society, where a healthy beard was a sign of wisdom and knowledge. But then Alexander the Great came along and changed all that, for the sake of the military. He forced his soldiers to shave for fear that an enemy could use a man's beard to his disadvantage in close combat. He thought that the enemy would grab it during hand-to-hand struggles, though I would be more worried about the pain of someone ripping my beard off. In contrast, the slaves, who were normally made to shave, were then ordered to grow out their stubble. Far be it for slaves to be equally fashionable as their masters.
The beard eventually came back into fashion, but a few rulers objected to their presence. In 1698, Peter I of Russia commanded his courtiers and officials to cut off their beards. To add insult to injury, he would sometimes personally shave the beards of his noblemen. Those wishing to keep their beards had to pay a tax - 100 rubles each year - as well as carry around a medal proclaiming that "beards are a ridiculous ornament." A similar taxation was passed by England's Henry VIII in 1535 - who, hypocritically, continued to grow a beard of his own. It's good to be the king.
The growing (or cutting) of a beard has had some important symbolic references in the past. Roman boys would not remove any facial hair until they had reached adulthood, then would shave as an offering to the gods. More towards the East, one punishment for crimes was to have one's beard removed in public. In America, an Amish man will keep a clean-shaven face until he has married, after which he will grow a beard which he will keep forever. In the Chatti, a German tribe, a man was not allowed to shave until he had killed an enemy!
In modern times, many police and military forces prohibit beards for one important reason that came up during World War I. In order to get a clean seal on a gas mask, you must have a clean face, so soldiers made sure to shave. They may or may not have been worried about the pulling of beards during hand-to-hand combat, as Alexander the Great was. Regardless, in a choice between shaving my beard and dying a horrible death via biochemical warfare, I'd go with the one that involves staying alive.
Of course, I cannot grow a beard, and maybe I should be grateful for that. Given the colorful history of beards, I may be better off without one.