ABSTRACT
Many male primates look different from females. The differences range from the bright blue testicles of vervet monkeys, to the thick beards covering the protruding throat sacs of howler monkeys (and some human necks), to the razor-sharp canines that a baboon’s lips can barely conceal (Figure 5.1). Such flashy signs of primate maleness seem like cumbersome attachments to the more svelte, streamlined forms that females take (Figure 5.2). Whenever the sexes differ from one another in body size or form, it is almost always the males that are larger, brighter, or more elaborately endowed (Figure 5.3). Why do the males of some species carry such excess baggage around with them, while others blend in with females so well that their sex can only be visibly distinguished by their telltale, but otherwise unremarkable, genitals?
