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Animal profile
Mandrillus sphinx
The mandrill is the largest monkey in the world, with a heavy build, a short tail and a ridged, brightly coloured face in adult males. It moves mainly on the forest floor in very large aggregations. Despite an old common name, it is not a baboon.
The blue and scarlet of an adult male mandrill's face and rump is not fixed decoration. Colour intensity rises with testosterone and dominance and visibly fades within weeks when a male is displaced, making the signal a running report on current status.
The scarlet and blue skin on an adult male mandrill's muzzle is not fixed decoration. Its intensity rises and falls with testosterone and social standing, so a male who loses his position fades, and the colour signals status to rivals and females alike.