 In fact, through observations across various species and cultures, it can be confirmed that the act of kissing and premastication has most likely evolved from the similar relationship-based feeding behaviours.Kissing is a complex behavior that requires significant muscular coordination involving a total of 34 facial muscles and 112 postural muscles.The most important muscle involved is the orbicularis oris muscle, which is used to pucker the lips and informally known as the "kissing muscle".