I wonder what evidences Cordain is ignoring. Indirect data of few population living on a peculiar diet isn't an evidence against scientific data of the metabolic effect of foods and elements. The effect on the mineral balance of foods have been studied seriously so much that you can say how much for example calcium is lost when a food is eaten, gram of food per mg of calcium.
I have to admit I don't know much about Masai and Samburu but I suspect they eat milk too. Well, milk has a positive effect on the calcium balance other than being an high carb food and having nothing to do with a paleolithic diet or a natural human diet.
And alkaline water is not enough to buffer the effect of an acid overload, not even 3000 mg of calcium itself are not enough to.
But of course it would be naive to say the least to consider these indirect data about the diet of few traditional poulations as the basis to claim whether a pure carnivorous diet is the natural diet of humans.
There's more to understanding our natural diet than reading what Masai or even Bushmen (completely different diets, yet both population appear to be healthy) eat.
I think that in certain population living a peculiar lifestyle generation after generation there may have been physiological adaptation and also that humans being omnivorous can sustain their health for long period of time eating almost anything, there was a population in the Borneo who ate nothing but radishes and sweet potatoes and yet they were free of diseases and fit. Then again my granmother eat nothing but refined grain products, smokes a lot and drink alcohol and she is healthy in spite of her age.
These anedcdotal facts are totally useless, those are not the proofs that tell us what diet is healthy nor what diet is the natural one for humans.
Clearly there are people who in spite of eating nothing but cooked meat without consuming the whole animal raw still can sustain themselves for a long period of time.
And clearly we can totally divert from our real natural diet by adding food that we can obtain through human manipulation of nature, so for example a diet of meat and milk would provide what naturally the plant food should have provided.
But to say that humans are born to be carnivorous and are supposed from the first day they were put on earth to eat nothing but meat is really throwing the baby with the bath water and refuting the anatomical and physiological evidence, if the real human diet is totally carnivorous we should be completely different within and I don't think someone supporting this theory lacking any sort of anatomical, physiological, biological and scientifical evidence can call a theory supported by dozen of studies simplistic.
That's clearly double standards as nothing could be more simplistic and absolutely theoretical than claiming that humans are natural carnivorous meant to eat nothing but meat to be healthy.
Yes, humans fly but humans were never meant to have wings and anatomy and physiology couldn't be clearer about this.

David