A cheeky Celebes crested macaque named Naruto, who snapped a few selfies with an unattended camera in Indonesia’s Tangkoko, has shot his entire species to fame. The photos went viral, and garnered the yaki, as they’re locally known, legions of fans worldwide. A high-profile lawsuit ensued - does Naruto own the copyright to his photos? The answer was no, but all that publicity was probably just what was needed to boost awareness of the conservation needs of this relatively unknown primate.

The type of toothy grin, as seen in Naruto’s selfies, is thought to be a display of ‘peaceful intentions’. Males often ‘yawn’ to display their canines and assert their superiority. To show aggression, male macaques stare open-mouthed, grin with lips closed, then yawn and give chase. A grimace and lip-smacking signals submission or satisfaction. A loud, bird-like call may be used to resolve conflicts, to warn others away or to indicate dominance in contests for females.

Every male and female macaque has multiple mates. When females are ready to mate, their rump swells and becomes bright red. The swelling may appear grotesque to us but it is an important visual signal of fertility. Olfactory cues may be at work too - males are seen to sniff the females’ rears at this time. Butt-sniffing is also a form of greeting, as is embracing, especially among the females. Female form more egalitarian bonds, whereas males conform to a strict pecking order.