Both series involve modern American families on inflatable rafts "tumbling" down dangerous bodies of waters and ending up in prehistoric worlds, for example.
Each episode involves one family teaching the other family a lesson in tolerance and diversity. The differences in evolution don't matter, the show informs us as viewers; we can still be "good neighbors."
For instance, "Forbidden Fruit" involves the Butler family discovering a stash of delicious tree-growing fruit. However, the cavemen, led by Gorok, forbid the family from eating it.
In the end, order is restored and Gorok provides viewers with the lesson of the week. "We have laws and customs," he reminds the Butlers. "You know things we do not, and we listen. We know things you do not...and you listen."