I am currently reading my way through a long list of science fiction and fantasy titles. (http://www.npr.org/2011/08/07/138938145/science-fiction-and-fantasy-finalists if you are interested in the list).
This book is an excellent antidote to all the paleo obsession of recent years. Yes, we may look physically identical to paleolithic humans, but we've come an awfully long way out of the stone age.
The author explains very well how humans have continued to evolve, whether we perceive the small differences or not. I am reminded of several species of birds where one has to analyze genetic material to tell them apart--sometimes big differences can go undetected except at the genetic level.
I can see where the simplicity of the Paleo thesis appeals--people are always longing for a past Golden Age and the current world always seems corrupt. I always enjoy the Cicero quote, "Times are bad. Children no longer obey their parents, and everyone is writing a book." We've been bemoaning the state of the world since at least Ancient Roman times.
As far as diet and exercise go, if people want to pretend to be cavemen (or cavewomen for that matter), I think it is a relatively harmless hobby. I do take a bit more exception to the assumptions about the proper role of women made by some of these people. I have no desire to return to the cave and cook a bison roast over the fire, thank you. But I do recall going through a phase as a teenager when I read a lot of books about the European settlement of North American and wished I could be transported back to that era. Their lives seemed much more exciting and meaningful than my own life did to me in that moment. Now that I am in my 50s, I'm just thankful that I live in the 21st century and have a warm home, a comfortable bed and a working kitchen. I don't belong in the past and I have a perfectly lovely present.
I'm as guilty as the next person of believing evolutionary just-so stories--they're fun, after all. But this book has helped me attain some perspective on the matter. I found the style to be quite easy to read and understand and although she pokes holes in a lot of balloons, it is done without cruelty. A plea to get people to actually think through some of their assumptions.