One key argument against this kind of thinking is that it arbitrarily singles out one time period. Most of the human genome, and human metabolic systems and body structures, is shared with chimpanzees, or even fish, and has evolved over tens or hundreds of millions of years. And humans have continued evolving over the last ten thousand years. So why obsess just about the Paleolithic?
Zuk focuses on those last ten thousand years, looking at some of the latest work on recent human evolution. One argument here is that larger modern populations have greater chances for positive mutations. Mostly Zuk targets specific claims, however, working through ideas about milk drinking, grains and diet in general, exercise, sexual relationships, family structures, and medicine. She concludes by addressing claims that human evolution has stopped or at least slowed drastically.
But she never really highlights the relative weakness of paleo lifestyle arguments. Imagine if someone planning a hiking trip in the Alps were to scorn modern topographic maps in favour of reading studies of the Himalayas, using those to reconstruct what the Alps were like millions of years ago, and then using that as a guide to the present. This is clearly confused, but it is basically how the paleo arguments work. When it comes to diet, to take one example, we have a wealth of observational information about human nutrition, ranging from biochemical studies of metabolism to large-scale epidemiological data. Given this, making dietary decisions based on a tenuous reconstruction of human diets during the Paleolithic, via studies of contemporary hunter-forager groups, is a stunningly bizarre idea.
In a few places Zuk's criticisms are along the lines of "why are these people using nineteenth century accounts of the Himalayas when there are much more recent studies?" and occasionally she's just presenting alternative "just so" stories. Her focus is on relatively robustly reconstructible recent human history, however, and she is mostly skeptical about the application of the material she presents to practical problems.
Paleofantasy remains focused on the science, with Zuk making no attempt to explore why people are drawn to paleo lifestyle ideas or how those fit into the broader history of stories and tropes about human evolution. And her sampling of ideas from Internet forums and popular articles is hardly systematic.
While Zuk's smacking down of wacky ideas is fun, it's also a little distracting from the actual science. Just as books on evolution that take refuting creationism as a starting point seem a little scattered, so too with a framework based on paleofantasies which are themselves inconsistent — there is no single "paleo" position on any of the topics covered. I enjoyed Paleofantasy, but suspect I might have enjoyed even more a (hypothetical) book by Zuk that more straightforwardly addressed human evolution over the last ten thousand years.