"Less Meat, More Vegetables" And Adaptationism
However, he ventures into questionable territory when he sings the praises of "cuisine" -- the package of menus and eating habits developed by any culture other than the industrialized West. Certainly most such cuisines are better for humans, animals, and ecosystems than the standard American diet. But Pollan's rationale for believing so has a strong adaptationist flavor.
Adaptationism is the idea that whatever has existed for some period of time must be optimal, because if it wasn't it would have caused its carriers to die out. In biology, an extreme adaptationist stance is generally rejected -- selective pressure is simply not strong enough, bad features are often side effects of good ones, and the range of options that selection has to work with is limited by evolution's lack of foresight. A similar case can be made against cultural adaptationism.
First off, the human body is a rather resilient contraption. So people can live on suboptimal diets, mitigating the selection pressure that Pollan relies on to refine cuisine. Just consider the example of the industrial Western diet, which in its modern form has lasted close to a century -- and which shows few signs of being brought down anytime soon by its own unhealthful effects. Pollan claims that modern Americans are evading selection pressure through modern medicine. However, access to modern medicine is far from even in our society, and the uninsured poor show no signs of eating healthier than the rest of us.
Human resilience means that there is room for other factors besides healthiness to affect cuisine. It can be shaped by environmental and technological constraints, as well as other cultural goals (such as kosher laws that served to mark Jews' separateness from other tribes and commitment to their god).
Then there's the question of whose eating habits define a culture's cuisine. Societies are not internally homogeneous, and what the upper class eats will be quite different from what the lower class eats (and even in classless societies like hunter-gatherers, dietary differences were present between genders, ages, or clans). Which is healthier -- the pre-industrial English peasant's bread and water, or his Lord's three meals a day of duck? The poor face obvious constraints of access to food which would seem to compromise their cuisine's optimality, but the rich had more non-health considerations (such as impressing others) that they would base their eating on.
All these theoretical considerations can be borne out by considering the suboptimal actual cuisines eaten by some cultures. Consider, for example, the Selk'nam people of Tierra del Fuego. Their diet -- which was sustained over a far longer time than modern Indian or Italian cuisine has existed -- consisted almost entirely of guanaco meat (so much for "less meat, more vegetables"). Or try the Fort Ancient culture, which inhabited Ohio in the early part of the last millennium. The Fort Ancient were often dead by 30 with all their teeth rotted out, because their diet was 50%-90% pure corn. I wouldn't recommend anyone today eat like a Selk'nam or Fort Ancient person if they can avoid it, but both would meet Pollan's criterion of "cuisine."