Kissing may have originated when mothers orally passed chewed solid food to their infants during weaning.
Food Joke
A length of Rope went into a bar, sat on a stool, and ordered a beer. The Bartender said, "We don't serve Ropes here." Dismayed and disappointed, the Rope went out and then got an idea. He stopped a man and asked, "Will you please tie a knot in me and separate my strands at both ends?". The man obliged, and with this done, the Rope went back into the bar and again ordered a beer. The Bartender looked him over and said, "Say, aren't you the same rope who was in here before? " "No," was the reply, "I'm a frayed knot."