* Kissing is a complex behavior: While many primates display affection and social grooming, "kissing" in the human sense is probably unique to us.
* Tongue use varies: Some primates do use their tongues for grooming or social interactions, but it's not clear if they do it in the same way we do.
* Limited research: There's not much research on the precise tongue movements used by primates during social interactions.
Here's what we do know:
* Chimpanzees and bonobos: These primates often engage in "lip-smacking" or "mouth-to-mouth" contact as a way of showing affection or reconciliation. However, we don't know if this involves tongue use like human kissing.
* Proboscis monkeys: These monkeys are known for their "kissing" behavior, where they rub their noses together. This is likely more about scent communication than actual lip contact.
In short: While some primates might have behaviors that resemble kissing, it's likely that true tongue-based kissing is unique to humans.