Gelada baboons are not actually true baboons, although they look very similar and are easily recognisable by the patches of hairless skin on their chest, which turns crimson when females are in oestrus. They are in fact the last surviving species of a once widespread group of grass-grazing primates. Geladas live in large groups of as many as 600 members. Such a complex society requires clear communication, and geladas use visual signals, such as facial expression and body posture, to interact.

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