>He points out that Mercader found sorghum residue on tools that likely wouldn't be used to process cereals, such as drills

An early form of the culinary arts?

Kidding aside, I have to say I've never subscribed to the same "perfect noble savage" philosophy that many on this list seem to embrace. Since early man was supposed to be as smart as we, and presumably just as curious, I find it hard to believe that they somehow avoided experimenting with many of the foods available to them. In fact, it's pretty ridiculous to assume they followed any kind of "dietary philosophy" unles there was a religious aspect involved. I'm willing to bet the general attitude was "if it don't kill me, it must be good to eat".

But, as Jim states, how widely spread and how frequently is the real question.

(A funny thought occured to me as I was writing this. Can you image a bunch of paleos sitting around the campfire, eating big chunks of meat, saying, "You know, we just aren't as healthy as our ancestors were. Maybe we should go back to a diet of insects and fruits" :))