I am in awe of the winners of The New Yorker's cartoon caption contests. The cartoons have at least two actors (sometimes human, sometimes other species), with one actor clearly the speaker. A funny line never enters my mind as I scan the latest entry.
Sometimes, the cartoon is set in prehistoric times, featuring cavemen commenting on a situation, perhaps a painting on the wall of a cave. What if the cave paintings of Lascaux and Altamira were actually cartoons, and cavemen (the women were probably working and not seen fit to take part in this intellectual challenge) were trading captions near the fire. That would be really funny!