Flea experts tell us that a flea can jump about 8 inches.  This natural capacity to jump about 180 times their body length is fairly amazing in and by itself.  Now, put a population of those fleas that can jump 8 inches into a container that is 4 inches tall for 3 days.  You can pull the lid off that container after 72 hours, and that population of fleas that can jump 8 inches will not leave the container! In just 3 days, they have been trained to only use half of their capacity because of their capped experience.