The hunter-gatherer diet is clearly the healthiest there is, and most people from over 10,000 years ago died because they fell off a cliff or froze or got eaten by a carnivore or the like...there is zero evidence of heart disease before the Egyptian mummies (though admittedly, there's precious little evidence to be found one way or the other). Not only that, but before the agricultural revolution, people were a good foot taller! There is no tooth decay ever, until that point, and there's plenty of evidence for that.

Maybe he'll enjoy Jared Diamond's The Third Chimpanzee, a broad-ranging book on evolutionary biology. There's a chapter on the human costs of eating grain, which include not only health costs but the beginning of the oppression of women, the invention of slavery, and more. Otherwise, I'd start with the paleodiet links page (http://www.panix.com/~paleodiet/)to discover much more info, some of it anecdotal, but much of it well-researched. I especially like the Weston Price Foundation pages.

About the safety of dietary fat, have him read the Science article. http://ajdubre.tripod.com/Health/So...ietaryFat0.html

Remind him that once, everyone "knew" that leeches were a great way to heal people of variouly maladies. The more educated you yourself are, the more readily you will be able to respond to doubt in anyone.

Best of luck to you!