Why Do Baboons Have Red Bottoms? [Everything To Know]

As primates, humans and baboons have a lot in common. In particular, our reproductive cycles and mating processes are similar. One thing that baboons have that we don’t, however, are colorful backsides.

This striking characteristic is usually only present at certain times, though. Only one species has a pink or red bottom all the time.

Female baboons have red bottoms during ovulation due to hormonal swelling. Once ovulation is over, the swelling goes down and the red coloring fades. Most male baboons do not have red bottoms except for hamadryas baboons. These baboons have pink or red bottoms regardless of their reproductive cycles.

Baboon Red Bottoms Are A Sign Of Ovulation

Female baboon anatomy is like that of humans. Their reproductive cycle is also similar, with a roughly month-long menstrual cycle.

Baboons are also non-seasonal breeders. They can mate and produce offspring year-round, similar to humans.

So, it’s important that males know when females are ovulating for a better chance at reproduction.

Red bottoms on female baboons are one of those signals. Hormones from the ovaries cause the skin around a baboon’s genitals to swell. This turns them pink or red and protuberant. The term for this effect is “tumescence.”

Once ovulation is over, different hormones bring down the swelling. This means that the productive mating period is over for the time being.

Experts understand the physical aspect of how these red bottoms happen. But the reason for this is up for debate.

It could be a way to attract specific mates or increase male competition. It could also be protection, as males have to work to defend the partners they want.

Male Baboons Don’t Prefer Larger Bottoms

The long-running theory regarding baboon bottoms and reproduction relates to size.

In theory, the male baboons prefer the females with the biggest bottoms. More swelling means the female is more likely to be reproductive.

However, a 2015 study shows that this is not the case. There is no correlation between fertility and bottom size. Male baboons also do not show a preference for larger bottoms.

Instead, males keep track of a female’s sexual cycles using the swelling. They prefer mates that have a higher number after their last pregnancy. In other words, male baboons prefer time over size.

Like humans, there’s a waiting period for female baboons between giving birth and being ready to conceive again. They may still ovulate, but it’s not a guarantee of fertility.

Just because a baboon’s backside is swollen, it doesn’t mean that they’re likely to conceive. So, males wait and count cycles to increase the likelihood of reproductive success.

Hamadryas Bottoms Are Always Red

A red bottom is not always a sign of mating readiness; in fact, it’s not even just for females.

There are five species of baboon in the world. These are the olive baboon, yellow baboon, sacred baboon, chacma baboon, and the Guinea baboon (Papio anubis, P.cynocephalus, P. hamadryas, P. ursinus, and P. papio).

These primates live across Africa and the Arabian Peninsula. All baboons have “ischial callosities” or sitting pads. These are thick layers of tissue similar to callouses that cover their hip bones and rears.

Sacred or hamadryas baboons are notable for their large and colorful sitting pads. In both males and females, the skin around these sitting pads is pink or bright red.

Their ischial callosities give them backsides that appear rough, puffy, and large. This is their natural appearance throughout their lives. It has no bearing on their gender or reproductive status.

In fact, for all baboons and Old-World monkeys, the sitting pad is about comfort.

The common theory is that they need the extra padding for sitting. It gives them better sleeping and feeding positions in trees. The pads themselves don’t relate to reproduction.


There are two reasons why a baboon may have a backside that appears red. The first is an attribute of all species of baboons. It involves their reproduction cycles.

When a female baboon is ovulating, the tissue around their bottom swells. This lets potential males know that it’s time to mate.

Another reason for red bottoms relates to species. The hamadryas or scared baboons naturally have red seat padding on their behinds. All baboons have this padding. However, only hamadryas baboons have pink or reddish coloring.

Male and female hamadryas baboons both have these reddish bottoms. A female’s behind will still swell and turn redder during ovulation like in other baboon species. But after their cycle starts again, the seat padding will still be pink or red.

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