Most likely, the near simultaneous birth and death of civilization. This is a story about, at once, the beginning and ending of civilization. It is the dawn of time. Ralph does not know about the existence of Fred and Sam. Their entire economy is based on the harvesting of trees.
Trees provide everything - food, clothing and shelter.
Fred's culture lives in equilibrium with that harvesting rate. This equilibrium is a primitive example of the Gaia Hypothesis that suggests all systems on the earth are connected and feedback to one another. Sam would like to improve Fred's productivity and invent leisure time so that Sam can sell video games to Fred's culture to cope with leisure time. So Sam would often go off and think by himself.