Question: Why is a baboons bottom red?

Suzanne Harvey answered on 20 Jun 2013:

Classic baboon question! Actually a lot of monkeys have big swollen red bums, and I have colleagues who study this topic 🙂

It’s actually quite complicated, but the basic idea is that females have these swellings to attract males – larger, brighter red bums look really odd to us but are attractive to baboons. Also, they don’t have them all of the time. From looking at a baboon’s bum you can tell whether they are fertile – a big red bum means the baboon can get pregnant, if she doesn’t have a big swollen bum then she can’t!