"Darwin had a big one. As did Plato and Aristotle. Pythagoras most certainly had one, a long one judging from his statue. Leonardo da Vinci’s grew to illustrious lengths later in life. So why, if all these famous scientists had beards to stroke when being clever and contemplative, is sporting facial hair in the lab a big no-no? Well, it appears that facial hair provides a massive substrate on which bacteria can frolic and play. So much so that a bearded man wearing a face mask sheds significantly much more bacteria than a non-bearded man or woman. In fact the risk posed by the facial hair bacterial fallout is such that the authors of the February 2000 paper in Anaesthesia end their abstract with this line: Bearded males may also consider removing their beards. So it appears that a responsible doctor in this day and age should be sure to shave." - Kurt Starnes