Why do monkeys boop? Social tolerance underpins muzzle contact in vervet monkeys

What is it about?

The internet is obsessed with boops. But why do animals touch noses, also known as muzzle-muzzle contact? Here, we look at the role of muzzle contact in wild vervet monkeys (Chlorocebus pygerythrus). Most initiators of muzzle contact ate after contacting someone who was also eating, suggesting that vervets are gaining information about food during muzzle contact. We also found that the clearest indicated that predicted whether a muzzle contact would happen was social tolerance between those involved, meaning that animals only contacted others they knew would put up with their intrusion.

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Photo by Ivan Sabayuki on Unsplash

Photo by Ivan Sabayuki on Unsplash

Why is it important?

Muzzle contact appears to be a common behavior in social animals, but there not many have tested why animals like to touch noses. Here, we tried to fill this gap for vervet monkeys, first by determining what muzzle contact looks like (who initiates and who receives). Next, we tested whether vervets are using muzzle contact for the most common reason given in the literature--to figure out what others are eating. While we find some evidence that vervets can use muzzle contact to gain information about food, our findings do not show that this is overwhelmingly so. Instead, our results show that vervets contact others that will tolerate them, rather than animals who likely have food information. However, if vervets gain information about food by contacting another who is eating, as well as eating something rare, they do appear to immediately use this information by eating themselves after contact.

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