Blue balls

Blue balls

Here is a fun experiment. Catch a vervet monkey, paints its balls bright blue and let him back into a cage with other members of his troupe. Your fine brushwork would have elevated his status in the troupe and the other monkeys with paler blue balls are behaving as his subordinates.

This was an experiment performed to understand the relationship between secondary sexual skin color and the status of the monkey in its troupe. Many primate species have colored sexual skin (pads in its bottom) and the face also. In rhesus macaques reddening signals readiness for mating, but in vervet monkeys they signal the position of the monkey in the social hierarchy. Male monkeys with brightest blue testicles in a troupe get to mate with his choice and boss the other males who have paler shade of blue testicles.

So blue balls are not always a bad thing….at least for the vervet monkeys.