Red butt

All primates, including monkeys, apes, and humans, have excellent color vision. This has led to monkeys using color, including colorful bottoms, in order to communicate non-verbally to other monkeys. There are several monkeys with red or dark pink butts, including baboons, mandrils, Japanese macaques, Rhesus macaques, Celebes crested macaques, and chimpanzees.   What Monkey Has …