This elusive inhabitant of equatorial African rainforests is the biggest of all monkeys and arguably the most beautiful. The 30kg males - three times the weight of females - are adorned with a golden mane and striking blue and red swellings on the face and hind-quarters.
The skin colour and pattern permit males to display their social rank and status to other males and communicate their genetic healthiness to prospective female partners. In a society where physical fights can result in injury or death, having a bright, communicative face might just save your skin.
They are also equipped with canine teeth that are amongst the longest of any primate. These are wielded in fights with rivals over dominance. And yet despite the damage they are capable of inflicting - or perhaps because of it - they are used in anger only rarely.
Most disputes are settled without the need for violence. A male’s colouration is a reliable signal of his fighting ability - the brighter the colours, the stronger the male. This allows weaker males to bow out gracefully before push comes to shove. Blood is spilled only when two competing males are closely matched colour-wise
