If you need to ask why they are isolated on this spacecraft, and what the human eats, then you miss the point of the whole endeavor. Hey, not only is this a TV show, it is also absurd buffoonery. What makes this experience so entertaining is the patter of comments thrown out by these two bots. Here are a few clips:
...or go to You Tube and find a gold mine of historical humor embedded as Mystery Science Theater 3000.