New In Paperback Jan. 30-Feb. 5

David Levithan, an editorial director at Scholastic Books and a popular author of young adult fiction, brings ingenuity and a wry edge to his first adult novel. The Lover's Dictionary cleverly uses about 200 unorthodox word definitions, from aberrant to zenith, to tell the story of a couple who meet online, move in together and struggle to weather infidelity. The cheated-upon, steadier mate, who narrates, is male, but it's deliberately unclear whether his poorly behaved lover, who comes from a less happy home and drinks, flirts and buys shoes to excess, is male or female. Amazingly, it doesn't really matter.

When food writer Jessica Harris first visited Senegal, she scoured the markets and cafes for traditional foods like the savory stew called "chicken yassa" and found that the flavors were already familiar. In fact, Harris found, many of the classic foods and flavors of African-American cooking come from the African continent. She traces that journey in her new book, High on the Hog.

Astronomer Mike Brown didn't mean to kill Pluto — or so he claims in his new book, How I Killed Pluto and Why It Had It Coming. Brown says the ex-ninth planet was just collateral damage in his search for the 10th. When Brown did indeed find a 10th planet, the International Astronomical Union made a shocking choice: It demoted both Pluto and the new plant to dwarf planet status, ruling that the solar system contains a mere eight planets, and raising the ire of elementary school students everywhere.

To trace the story of the human heart through the world of science, history, culture and our bodies, novelist Stephen Amidon collaborated with his brother Thomas, a practicing cardiologist. "One of the things that surprised me during the course of writing this book was how durable the heart's metaphorical power has been — not just in the past 50 years in the great explosion of cardiology, but in the past 500 years, since the great anatomists of the Renaissance began opening up bodies and began looking at the physical heart," Stephen Amidon said on Weekend Edition Saturday.

As dogs age, taking care of them becomes more difficult. Issues like dementia and incontinence arise, as well as navigating the maze of end-of-life care decisions. Good Old Dog is a reference guide for owners of older dogs by veterinary behaviorist Nicholas Dodman in collaboration with other vets from Tufts University, as well as writer Lawrence Linder. It offers welcome advice on handling changes in the metabolism, heart and digestive functioning of older dogs, among other topics.