3 min read

5 Very Unusual Things That Monkeys Find Sexy

1. Squirrel monkeys get BIG to attract mates.

[Ahmed Amanatullah via Flickr]

When it's mating season for the squirrel monkeys, the most successful males fatten up. Anita Stone, a primate expert at Eastern Michigan University, writes in a recent study that the beefier males spend "more time near females and less time alone," engaging in more social and sexual activity with the females.

2. Mandrill butts are blue.

[Brian via Flickr]

The rumps of mandrills act like colorful signs of availability, with the dominant males having the brightest hinds (bright blue and red, to be exact). During mating season, female mandrill rumps also undergo "sexual swelling," indicating their fertility.

3. Howler monkeys shout for mates with impressively loud yawps.

Howler monkeys, considered the loudest land animals on Earth, let loose yells that can be heard up to 3 miles away. But all that noise isn't for naught -- the sounds of the male monkeys draw in females, and let other monkeys know when mates are claimed.

4. Male tufted capuchins use their pee like cologne.

[Kenny Ross via Flickr]

For years, capuchin monkeys' "urine washing" behavior -- in which male monkeys rub pee into their fur -- had perplexed scientists. But an MRI study of female capuchin monkeys shed light on the mystery: Female capuchin monkey brains reacted to the urine of adult males (but not to the pee of young or other females). In light of this research, Kimberley Phillips, a primatologist at Trinity University in Texas, told The BBC she believes male pee communicates sexual status.

5. Female proboscis monkeys appreciate a big nose.

[YouTube]

Although researchers aren't entirely sure what the male proboscis monkeys' big nose does -- it could keep them cooler or make their honks louder -- the most prevalent idea is that female monkeys prefer males with the biggest schnozzes.