Mary Roach is at her strongest when she reveals hitherto unknown stories of science. The more she gets stuck in the technical details, the harder it is to keep reading.

Grunt does a decent job of focusing on stories, especially scatological stories that often go untold. I found the chapter on food poisoning particularly entertaining.

What keeps grunt from 5-star is a consistent dance around the consequences of war. Roach explains that she doesn't want to include anything about killing. This pacifist approach sacrifices more substantive analysis to keep the light-hearted tone. This makes the entire book feel incomplete.

Grunt provides a wealth of factoids to bring up at less fancy parties. Which is always a good thing.