Australia actually found that the Beard can block up to 95% of UV rays from the sun - which can prevent freaking skin cancer. The Beard does also act as an evaporative cooler as well, as sweat from the skin evaporates and creates a flow of air out of the Beard which has a cooling effect. Combined with the shielding effect of the Beard, this can keep you even cooler than not having a Beard at all!
Beards can reduce anywhere from 50-95 percent of the ultraviolet (UV) rays reaching the skin underneath, according to a study conducted by researchers in Australia. "Facial hair has an Ultraviolet Protection Factor (UPF) of anywhere from 2 to 21," says Alfio Parisi, one of the study's authors and professor of radiation physics at University of Southern Queensland in Toowoomba.
UPF is the system of SPF (Sun Protection Factor) that's used for apparel, which, yes, UV rays can penetrate. A UPF rating of 15 is considered good, but the ratings go up to 50+, which is the most protective.
A beard can ward off throat disease.
Facial Hair can help keep airborne bacteria out of your mouth, which assists in protecting your throat. The effectiveness of the beard has been documented as far back as 1875! In the book Pulmonary Tuberculosis: Its Pathology, Nature, Symptoms, Diagnosis, Prognosis, Causes, Hygiene, and Medical Treatment, Dr. Addison P. Dutcher noted:
There cannot be the least doubt that the beard, and the hairs that grow in the nostrils, were designed by nature to guard the lungs from the invasion of these deleterious particles. Such being the use of the beard, individuals engaged in employments where the air is constantly filled with particles of fine dust should never shave. I have come to this conclusion from a careful observation of the effect of wearing the beard and of shaving upon the air passages and lungs. And I could, if space allowed, record many cases of throat and lung-diseases that have been permanently cured by wearing a beard.