It is to attract mates. Females mate more frequently with males with brighter, more colorful rumps. There's a study in which the researchers painted the genitals of baboons in Tanzania and studied the female responses; they found that the more turquoise the more the females were attracted. Furthermore, in geladas (closely related to baboons; sometimes called gelada baboons), the amount and intensity of the red marking on the chest is directly proportional to testosterone levels, so it is certainly in the realm of possibility that the rump coloring is also related to testosterone levels. So from an evolutionary perspective, if coloring corresponds to testosterone, a male with more coloring is likely more capable of defending a female and her offspring, making them more appealing mates.
sometimes
they need food!
When there bums are red that means that they can get pregnant again.
The ones that have been violated...
Baboons, they have big red rears!
squirrel monkeys and red bum baboons
By passing pass through their bums
Bums! Bums!
None, a group of Baboons is called a Troop.
Baboons are not extinct.
Because poo comes out of it are you stupid Need to get your head checked you wierdo
bums