Male baldness, like many things, is an inevitable sign of aging. Some men embrace their smooth scalps as evidence of plentiful testosterone—or unfortunate genetics. For those who prefer less shine on their dome, a new discovery offers hope for a long future of shampooing and haircuts. Male-pattern baldness affects tens of millions of men in America, with half of men experiencing some hair loss by age 50. Researchers recently discovered a much-needed clue to this condition by comparing the hairy and bald sections of men’s scalps. The hairless areas had a higher concentration of a protein called PGD2—short for prostaglandin D2. Other tests showed that this protein could slow or stop hair growth in tissue cultures of both mice and humans. The researchers also noticed that mice that were genetically engineered to produce high levels of PGD2 were bald as a…well, baby’s bottom. The good news is that previous studies have shown that bald men still have stem cells that can create hair. They also have hair follicles present, but the hairs produced are too small and thin to push through the scalp. The cure for baldness then, could be as simple as blocking the receptors for this protein in the scalp. In theory, this would stop—or possibly reverse—hair loss. Further study is needed, though. Researchers have to identify drugs that can block the activity of PGD2. Fortunately, several drugs already exist that do this. They are currently used for allergies and facial flushing, and some are already undergoing clinical trials. In the meantime, if things are starting to thin out on top, try embracing your new look as if you were an NBA basketball star or aging movie action hero.