Well, I'm biased. The opening chapter struck a chord; ten years earlier, in 1976, I'd accompanied Farish Jenkins, Chuck Schaff, and Bill Amaral on a collecting expedition in Montana. So I was hooked here from the get-go. Still, the title and topic seemed so far reaching that I purchased the book largely out of skepticism that anyone could address such a theme in a concise and coherent way. But as in his previous book, Your Inner Fish, Shubin maintains this interest with an enviable ability to connect disparate topics and events into a meaningful whole, just as he's done in connecting paleontology with cell and developmental biology in his professional life. He's able to balance technical detail with clear and entertaining prose. He strikes a good balance between personal anecdote and scientific exposition--and maintains that balance through the whole scope of the book. There is a tendency to oversimplify at times, and a few obvious proofreading mistakes--e.g., whales are derived from even-toed ungulates, not odd-toed--but these are minor issues; I very thoroughly enjoyed this and hope there's more to come.