Humans have a tailbone for a tail we don’t have, wisdom teeth that don’t fit in our mouths, and tonsils that only seem to cause problems. Each of these “mistakes” can tell us a little bit about how we evolved and why we were so successful in spite of these flaws. We talk about our body’s quirks with biologist Nathan Lents, author of “Human Errors: A Panorama of Our Glitches, from Pointless Bones to Broken Genes.”