In a 1985 study, Canadian chemist David Dolphin theorized that the root cause of legends of vampires and werewolves is porphyrias, diseases involving a malfunction in the biochemical production of heme, the blood's red pigment. Victims of such diseases are very sensitive to sunlight and can develop chemical imbalances that lead to the destruction of tissue. Dolphin suggested that some victims could develop fanglike teeth as gums were destroyed, and some might become very hairy. Dolphin also suggested that victims in the Middle Ages may have turned to drinking large amounts of blood for its heme.