“Paleofantasy”: Stone Age delusions

The evidence against cereals (and most especially wheat) seems in general to be much more widely accepted than that against legumes; take that as you will.

(Or to put it another way: "don't eat wheat" features in a lot more of the newfangled low-carbohydrate diets than "don't eat beans".)

Migration would slow down many kinds of evolution. Lots of interesting evolution happens when you get divergence in island (literal or metaphorical) populations.

Migration does mean that any clearly beneficial changes will spread quickly, and a large population gives more chances for them to arise - lactase persistence is probably an example of this. So humanity probably does adapt quicker than it otherwise would to changes in the environment, if those changes affect most of humanity.

In the short term I'd expect to see humanity getting better at a lot of things as races intermingle and previously separate gene pools combine - a lot of things like height or fitness or intelligence seem to be combinations of many genes where "perfect" is in some sense the default; how good you are is a question of how many "bad" genes you've picked up (and most of the bad genes are recessive). I've seen anecdotal suggestion that mixed-race children are healthier (would be interested to hear if there's any proper studies of this). I suspect in the immediate term this will be a bigger effect than that of new mutant genes.

Your metaphor of adding wet sticks to a fire is flawed, from a thermodynamics argument. Assuming that the fire is large enough, it will dry out the wet sticks through evaporation/boiling, and the wood's total contribution to the heat ("energy out") will be unchanged.

Now, of course for the people sitting around the fire, some of the heat that would be warming them up or used for cooking is instead used to force a phase change in the water, so it won't be as much "useful" heat, but that meaning of utility - which I believe is the one you want - is outside of thermodynamics.

For what it's worth, "for some very compelling anecdotal evidence" of the thermodynamic approach, see The Hacker's Diet at http://www.fourmilab.ch/hackdiet/ , which uses the "Rubber Bag" model. Unlike the garytaubes.com web site, the entire book and supporting materials are available for free download. The basic premise is the thermodynamic "if you eat more calories than you burn, you gain weight; if you eat fewer calories than you burn, you lose weight." (See also 'Food and fact' where "The rubber bag view of the body and considering only the calorie content of food is obviously oversimplified." and some of the complications are mentioned.)

I believe you are making a different argument, which is that you can't always measure the caloric impact of foods. Under the Hacker Diet, that makes little difference. It uses a feedback system based on weight trends rather than specific calorie counting. There's no need to know that oak combustion produces about 15MJ/kg and boiling water from room temperature takes about 3MJ/kg, because it only looks at 'is there enough heat'?

As far as I know, almost any diet that's not obviously insane or unhealthy gives satisfactory results if followed diligently.

It's not about the specific content, it's not about any pseudo-scientific justifications for the content, it's simply about how easy it is to stay on the diet without lapsing or indulging in any extraneous treats.

A quick search of PubMed finds some recent (within the last year) papers like:

http://www.ncbi.nlm.nih.gov/pubmed/23357955 - "Timing of food intake predicts weight loss effectiveness" It starts "Background: There is emerging literature demonstrating a relationship between the timing of feeding and weight regulation in animals. However, whether the timing of food intake influences the success of a weight-loss diet in humans is unknown."

http://www.ncbi.nlm.nih.gov/pubmed/23167985 - "Effects of exercise before or after meal ingestion on fat balance and postprandial metabolism in overweight men."; "It is unclear how timing of exercise relative to meal ingestion influences substrate balance and metabolic responses."

These make me think that there isn't "droves of scientific literature" which show the importance of meal timing in humans, much less characterize the magnitude of the importance. (Eg, if there's a measurable 1% difference in overall effect on weight then it's statistically significant finding, but almost certainly not enough for most people to care about.)