I got to the end and realized I'd been reading Robert Sapolsky.

His "Biology of Human Behavior" Stanford lecture course in about 25 parts is on youtube. It's absolutely amazing; he's a great lecturer, articulate, funny, fascinating, a great storyteller about remarkable experiments and legendary scientists. It starts with evolutionary biology/sociobiology and goes down via a dozen levels of explanation ('buckets' he calls them) to brains and genes and how they work, in quite a lot of detail. I couldn't recommend it any more highly. p.s. My girlfriend (very non-sciency) loved it too.