This book really deserves two ratings--one for the evolutionary science and one for its coverage of the paleo diet.
Paleofantasy has a lot to offer you if you are interested in evolution in general and human evolution in particular.
Zuk's central argument throughout the book is that evolution is a continuous process that didn't stop for humans in the paleolithic and that different traits evolve at different rates. She places particular emphasis on the fact that sometimes evolution can act very quickly, even in as little as a few generations. Of course the idea of rapid evolution is not new--it was termed "punctuated equilibria" in a 1972 paper by Niles Eldredge and Stephen Jay Gould.
Even as an avid reader of evolutionary science books, I was treated to several new examples of rapid evolution at work such as:
-The alternating increase and decrease of beak size in the same population of finches due to changes in weather and food availability
-Changes in breeding age and size of guppies due to placing them in environments with different levels of predation (an example of "experimental evolution")
-Decreases in fish size and breeding age as a result of human fishers continually removing the larger fish.
Of course the question we all really want the answer to is not just could rapid evolution happen in humans, but has it happened?
The answer is yes, and Zuk gives many examples including:
-Blue eyes were only thought to have arisen 6,000 - 10,000 years ago
-Rapid selection of the CCR5-D gene variant that makes some people immune to HIV
-Lactase persistence (production past the age of weening of the lactase enzyme that digests lactose in milk) is only dated back to about 7,500 years
Perhaps even more fascinating is that she describes ways that different populations of humans have independently evolved the same adaptation in different ways! The ability to digest milk into adulthood, for instance, arose as lactase persistence in some populations and increases in lactose digesting gut bacteria in others.
For the science of the book, I give it 5 stars. I was thoroughly entertained and learned a lot.
THE PALEO DIET:
Zuk's points about the fallacy of the magical 10,000 year barrier between us and the environment our genes were supposedly adapted for, the variety of diets different groups would have eaten during the paleolithic, and even the flawed notion of "perfect adaptation itself" are all well taken--and certainly correct.
However, in reducing what is actually being said by people in the paleo community to a monolithic, one-size-fits-all diet, Zuk commits one of the same fallacies that she sets out to debunk.
She references some of the well-known paleo advocates, but, troublingly, the primary source of what paleos are doing seems to be blog comments and internet message boards (long recognized as bastions of "intelligent" discourse...).
Moreover, she rubs many of us the wrong way with her continual characterization of people following the paleo diet as extremists who look down on using modern prescription glasses, donate blood to simulate regular blood loss, and eschew vegetables (in fact, many paleos claim to "eat more vegetables than a vegetarian").
Certainly shenanigans do go on in the paleo community, but at its core the conversation isn't, "was this food eaten 10,000 years ago?" but "is this food nutritious and does my body respond well to eating it?" The arguments for what exactly makes this so for a particular food are more nuanced than whether or not Grok ate it.
Lactase persistence, for example, is already well known in the paleo community. Mark Sisson advocates "n=1" individual testing in acknowledgment of the fact that we aren't all adapted equally to the same foods. The pre/post-agricultural era consumption of a food is only one clue to whether your body will respond well to eating it--not the final word.
Although Loren Cordain's formulation of the diet was rather strict in regards to dairy and grain consumption, ideas in the paleo community have, well... evolved since then.
Citing evolution of lactase persistence and increased amylase production--while very interesting and correct in their own right--as enough proof to categorically relegate the paleo diet to paleofantasy simply won't do. I would also like to have seen a nod to any research on gluten digestion--arguably the bigger concern with grains in the paleo diet.
As for paleo exercise, Zuk's conclusion that we are born to run based on adaptations like shorter heel bones and taughter tendons than our evolutionary cousins is convincing. However, one is baffled by citing these adaptations, persistence hunting, and the Endurance Running hypothesis as evidence that rejection of "chronic cardio" is against the science.
The average speed this book cites in a persistence hunt is 4 mph. Those are 15 minute miles, which is the speed of a brisk power walk at best. Allowing for tracking the more likely scenario is light jogs interspersed with walking and stops to examine clues to where the animal has gone. This bears no resemblance whatsoever to the modern activity of hours of continuous running at 2-3 times that speed--which is the type of "chronic cardio" activity that Mark Sisson and others are really speaking out against. Arguments against this type of chronic cardio include oxidative damage, increased cortisol (stress hormone), and drops in testosterone--not just that Grok didn't do it.
As for what the science actually tells us about diet, the conclusion I would reach is that on average we are still "better" though not "perfectly" (since we never were to begin with) suited to pre-agricultural era foods than post-agricultural era foods, with some of us faring better or worse than others with the newer foods. For example, the figure from this book only puts lactase persistence at 35% worldwide, with 80% the highest figure quoted for a population. This means that even in populations extremely well adapted (comparatively) to milk, it will cause digestive issues in 1 in 5 people. Compare that to a food like beef or blueberries where digestive issues are extremely rare.
I give this book 2 stars for its coverage of the paleo diet.
THE BOTTOM LINE:
Marlene Zuk takes us on a tour of recent findings in evolutionary science touching every corner of our lives from diet to exercise, love, and family life. Fans of evolutionary science will no doubt find Paleofantasy a page turner. For this reason alone the book is worth reading.
However, members of the paleo community will likely be disappointed if not offended by Paleofantasy. Zuk seems to go out of her way to highlight fringe extremists of paleo, while missing the nuance of what is really happening in the community. Which is unfortunate, because this book positions itself as antagonistic to the very target market it should have been written for. Though if you have sufficiently thick skin, you should still read it anyway.
Overall I give this book 5 stars for the science, 2 stars for coverage of the paleo diet, and an overall rating of 3.5 stars. Since Amazon doesn't allow half stars I've opted to round down to 3.
[Full disclosure: I consider myself a member of the paleo community, though I have also publicly blogged about things paleos believe that aren't quite right (do a web search for "7 Paleo Fantasies" if you're so inclined).]