Baldness and Male Pattern Baldness
Male pattern baldness occurs very commonly in humans but not in great apes. Male pattern baldness is a heritable trait carried and passed on by the mother that produces premature and sometimes extreme baldness in men. While there have been instances of "bald" great apes, their lack of hair does not follow the classic appearance of human male pattern baldness. However, Stumptail monkeys (Macaca arctoides) have traditionally been used by pharmaceutical companies to test products on male pattern baldness (even though in this species females also go bald on their foreheads with age).