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Yes, men and women eat meals. But they also ingest nutrients. They grind and sculpt them into a moistened bolus that is delivered, via a stadium wave of sequential contractions, into a self-kneading sack of hydrochloric acid, and then dumped into a tubular leach field, where it is converted into the most powerful taboo in human history.

Welcome to Digestion 101 with your instructor, the lovely and talented, Mary Roach. Today's lesson is Everyone Poops! Now Get Over It!

This is the truly magical, mystical and messy journey of how food goes in one end and out the other.

Keeping in mind that in her last book, Packing for Mars: The Curious Science of Life in the Void, Roach devoted an entire chapter to pooping in space, so be prepared for loads of unpleasant, yet interesting facts you could have happily gone your entire life without knowing. Probably the best example is the distinctions between the "sausages" on The Bristol Stool Scale. Don't even get me started on fecal transplants. (Yes, there is such a thing, and after Roach's explanation...it sounds like a perfectly logical and necessary procedure.)

If you can keep your squeamishness in check, you'll find that this is a hilarious, surprising, occasionally disgusting, and always amazing look at what goes on inside us all.