Life on Mars takes a satirical look at evolution vs. Intelligent Design — a sort of feint by anti-evolutionists to get creationism into the classroom by assiduously avoiding the mention of God. Instead, reference is made to a "higher" or "superior" intelligence. The novel's conceit is this: what if the Intelligent Design folks are right and the evolutionists are wrong?

What if a higher intelligence did indeed get the ball of creation rolling, only the intelligence wasn't God but an alien race ("The Spong") that had seeded earth as a botanical garden eons ago, only to return to find it contaminated with humans?

In preparation for a "Treatment" to correct their error, the Spong assign a human to act as earth's final biographer to provide them with proof of why humans just have to go.