Over the past year or two I've done some reading about the paleo diet. At at first glance, this seemed to make sense to me: That eating foods that humans had evolved to eat would be the best diet. And yet I couldn't buy into it. I kept having a feeling that there was something missing, some problem in the rationale that would blow the whole thing up. Besides the fact that historical humans didn't follow this diet and seem to have done okay. (Paleo advocates would no doubt tell me that historical humans would have done even better had they followed a paleo diet.) As I was fixing lunch today, the answer occurred to me: Peppers. As an SCA chef can tell you, peppers (along with tomatoes and potatoes) are a New World food. And so a quick web search was in order: Are peppers paleo? Apparently so. But unless you're Native American, your ancestors were only exposed to peppers for 500 years, certainly not enough time (by paleo standards) to have evolved the ability to process them.
Now, I'm not trying to take this as any sort of debunking of the paleo diet. (People who have such large amounts of time, energy, and money invested in an idea aren't so easily swayed.) And if you're currently eating a paleo diet and it's working for you, more power to you. But as for me, I no longer feel the compulsion (and certainly never felt a desire) to go paleo.
Additional trivia: While doing research for this post, I learned that 3 out of the 4 founding members of Black Sabbath are vegans. (Tony Iommi is the odd man out.)