Nothing attracts the ladies like a nice, big set of rouged lips. At least that seems to be a routine rule of mating for black-and-white snub-nosed monkeys (Rhinopithecus bieti), researchers report December 16 in Royal Society Open Science.
Some males of this species surround themselves with a social group of females, while others are relegated to roving bro packs. All males of this species display notably luscious, red lips — a natural lipstick of sorts.
Looking at a set of 15 snub-nosed monkeys in China, researchers found that lip color reddens with age among R. bieti males. During mating season, males living in harems monopolize females and sport brighter red lips, while bachelor males’ lips go pale. Lip color may be a status symbol for snub-nosed monkeys, the researchers write, either driven by female preference or male competition.