The concepts in this book were so nicely laid out that you keep saying to yourself, "Of course, it is so obvious!" This book reinforces the notion that nothing in biology makes any sense without evolution. My thoughts turn to intelligence and consciousness - hard to measure and describe, but surely based upon our physiology, which we seem to share with just about everything. So if all creatures great and small are using the same molecular machinery to get around, it seems resonable that they would also share the outcomes we think are uniquely human - consciousness, speech, intelligence, emotions, and so forth. Once again, unmeasureable, but perhaps better described as a spectrum vice a binary measure. Given all the similarities within the animals described in this book (wait a minute, does his argument extend to plants? Is there a sequel coming?), it would appear difficult to pinpoint what makes humans unique in these regards.