Either pout or open mouth kissing may result in mouth to mouth kissing if the other responds with similar behavior. Equally, two chimps open mouth kissing each other on the face may result in one chimp pressing his mouth over the other's upper lip and nose whilst the other has its mouth over the lower lip and chin of the first. An open mouth kiss with mouth over eyes and brow ridge is not uncommon. Kissing may be initiated by the higher or lower ranking of a pair. Pout kissing often occurs in greeting, submission, and reassurance.
Open mouth kissing frequently occurs during feeding or social excitement.