In what may be the most crowning achievement for the practice of dermatology in recent years, researchers at the University of Pennsylvania have finally unlocked the secret to male pattern baldness. According to the study’s author Dr. George Costarelis, a protein called Prostaglandin D2 (PGD2) is responsible for causing hair follicles to grow thinner and weaker as men age. He said that the study took samples from the balding scalps of men with male pattern baldness and tested them against samples from parts of the head that still grew…