From Dad

Dear Mike,
I continue to be vitally interested in my diet , but lack anything approaching certainty.
Our culture and lifestyle have changed markedly over the past tens of thousands of years ........ but I don't believe our basic biochemistry has had time to evolve much. If there was any good way to find out how the average of out distant ancestors ate we would have far better guide lines.
PROTEIN I cannot believe that humans of even 50000 years ago were efficient hunters of meat animals. They lacked running speed and endurance and even a good sense of smell. The only credible evidence is that of primiitive man digging pit traps where they may have even been able to trap animals as lerge as a mastodon ...... that would keep the tribe and surrounding tribes in meat for a few days of feasting ....... but no way that could be a steady and reliable source. If game animals are well equipped to survive predators as swift as the cheetah or as strong as the lion what chance did a human have.
Only with the domestication of the hunting dog and invention of the bow and arrow did humans become effective hunters, but that was 15-20 thousand years ago. The domestication of the horse, less than 10,000 years ago was another major step ........ then came agriculture, settled villages and herds of meat animals, all in the very recent past.
Much of our physiology, biochemistry and anatomy leans toward a herbivore wih a touch of omnivore but certainly not mch for carnivore.
Excessive protein in the human diet is almost certainly a slow poison to the kidneys and bone strength.
Plus a high saturated fat intake that goes with much of meat eating is a slow poison to blood vessels.
All fats were probably as difficult for very primitive people to find as animal protein ...... and they were likely to avidly eat insects, especially insect larvae and other small sources of fat and oil.
CARBOHYDRATE
Almost certainly primitive people had no access to the abundant carbs we get from wheat, corn, potatoes and a host of other sources ....... although the San people of the Kalahari (one of the last hunters and gathers that could be studied before civilization totally distorted them) showed that they got a big fraction, perhaps 50-80%, of their calories from starchy tubers. This is also supported by studies fro the Transvaall Museum, in Pretoria, of human tooth structure and dentine being almost identical to the teeth of the hairless rat-mole of Africa, that has a diet very high in starchy tubers. These primitive tubers are in general nothing like the potato in that they have far more fiber and require much chewing and saliva production before digestion.
MY BEST GUESS AT PRESENT is that real low carb intake (enough to suppress the appetite by developing ketosis) in not the way to go. Also pigging out on high carb foods is equally bad in that the excessive amounts of insulin released stimulate more hunger ....... which is OK if there is no loaded pantry. In the Fall our ancestors may have come across a wild fig tree, for example, and gorged themselves but there was probably not another tree at hand for the rebound, whereas we have carbs in excess around the clock.

Take a look at tis article ...... which has some good points ....... but overall is still far from a complete answer:

http://women.timesonline.co.uk/tol/life_and_style/women/diet_and_fitness/article4523487.ece