Before leaving the subject of Evolution, I want to emphasize the significance of it. Humans were hunter/gatherers for a long time - for their entire existence up until 12,000 years ago.  And, according to Evolutionary theory, 12,000 years is not long enough to bring about genetic adaptations. Therefore, we are still adapted to our original diet, the hunter/gatherer diet. Perhaps I should call it the HUNTER/gatherer diet because that’s how devotees really mean the term.  But, what really is a hunter/gatherer diet? It simply means that people ate anything and everything they could get their hands on that was remotely edible, and it was determined mainly by what was growing and living  and available in their range of travel. And that’s why hunter/gatherer diets vary so much in composition and proportion. The hunter/gatherer diet really isn’t a diet at all. It doesn't  specify anything.  We can speak of the natural diet of lions as antelope and zebras. And we can speak of the natural diet of zebras as grass. And we can speak of the natural diet of koalas as eucalyptus leaves.  But, the hunter/gatherer diet was just humans being opportunistic about food wherever they were. It had less to do with genetics and more to do with circumstances.  Why did the early humans of northern Europe eat so much meat? It wasn’t because of genes or Evolution; it was because of an ice age.  There are many theories as to what causes ice ages: variations in the sun’s output and reduced sunspot activity, wobbles in the Earth’s orbit, continental drift, etc. But, it was very unlucky for humans that an ice age had to come along during our early development. There we were losing our body hair, becoming relatively hairless, during an ice age.  And why did that trend continue? Why didn’t it reverse? Was it because we started covering ourselves with animal skins? But, we weren’t able to cover ourselves all that well.  It seems like Evolution would have “selected” more body hair, but it didn’t. The trend towards less body hair continued despite the ice age.  We need to admit that we do not know how and why life developed the way it did on Earth, including human life.

But, let’s move on to our next question for the paleos, and it concerns human protein needs. It is widely agreed among biochemists that most of the calories in food are used as fuel. We use proteins to build and maintain structures and to make various functional compounds, such as enzymes, hormones, and antibodies.  But our total need for protein isn’t that great. The US government, which is no enemy of the beef and dairy trusts, says that adults need about 60 grams of protein a day, which is about 2 ounces- a little more for men and a little less for women. 60 grams of protein comes to 240 calories, and if a man gets 2400 calories total, that comes to 10% of calories.  The government admits that there is a significant “safety factor” (excess) built in to that figure, and other organizations, such as the World Health Organization, cite a much lower requirement.

This issue of how much protein we need has been studied in great technical detail, including rates of enzyme turnover, rates of muscle tissue breakdown from exertion, rates of hormone, and immunoglobulin production, etc. One researcher who has studied it a lot is Dr. Mark Hegsted of Harvard University, and he concluded from his vast work that, based on all the considerations for protein utilization in the body, that humans need .8 grams of protein per kilogram of body weight.  So I, for instance, weighing 61 kilos, would need 48.8 grams of protein a day.

We know for certain that any amount of protein consumed above the basal requirement gets broken down, deaminized, and burned- either like a carbohydrate (as with glucogenic amino acids) or like a fat (as with ketogenic amino acids).  And for now, let’s put aside the whole issue of muscling-up and bodybuilding. Let’s just talk about people like myself: an adult who wants to stay fit and maintain his muscles but not grow them larger.  The amount of protein that I need to do that is not very much. And any protein I eat in excess of that is going to be dismantled and burned.

So, we can use protein as a fuel. So, what’s the big deal? The big deal is that 15% of the amino acid is nitrogenous, and nitrogen doesn’t burn. When that amino group (NH2) gets split off, it immediately tends to pick up another hydrogen (since nitrogen has three hands) forming NH3 which is ammonia.  You know how caustic and irritating ammonia is.  Burns the nose, right? Well, it burns inside of you as well.  The body has to get rid of ammonia pronto, so it combines two amino groups with one molecule of carbon dioxide to form a different substance: urea. Urea is essentially non-irritating. It is a waste product, but it doesn’t burn like ammonia.  So, it’s easier to handle. The more protein you eat, the more urea you form.  And the more urea you form, the greater the burden on your liver and particularly your kidneys.

If you don’t die of anything else sooner, you will eventually die of kidney failure. That’s because the kidneys are gradually breaking down throughout life. You’re losing nephrons, which are the functional units of the kidneys, and they aren’t being replaced.  And when you don’t have enough working nephrons any more, you either go on dialysis, or you get a kidney transplant, or you die.  There’s not much you can do for your kidneys, except not to abuse them.  You abuse them by taking drugs, drinking alcohol, and by smoking.  Excess salt  also abuses the kidneys. And excess protein abuses the kidneys as well, since the kidneys have to do the work of eliminating the excess urea.

Carbohydrates burn clean:  all the way down to carbon dioxide and water. Imagine if there were cars whose exhaust was nothing but carbon dioxide and water vapor. There would be no air pollution! And even fats burn pretty cleanly. They too, eventually, get  down to carbon dioxide and water- but along the way they form keto-acids which can cause trouble- but only if you’re diabetic.  But, proteins never burn clean.  You could say that proteins make black smoke.

People who eat high-protein diets tend to have higher levels of blood urea nitrogen (BUN). Ideally, BUN should be in the teens. I have even seen it in the single digits in people who  scrimp on protein. But people who eat high-protein diets are usually in the 20s, and sometimes in the 30s, and I don’t consider it a good thing or a harmless thing.  Why should turning the blood more urinous be considered OK?

So, my question for the paleos at next year’s Ancestral Health Conference is:

Since research, such as that of Dr. Mark Hegsted, has demonstrated a human need for protein along the order of .8 grams per kilo of body weight, what is the advantage in consuming vastly more than that, as people commonly do when eating paleo diets?  And even if you think it is harmless, what good reason is there to do it?  Why doesn’t it make sense to eat only as much protein as is needed to maintain bodily structure and function, and not use protein as a fuel?

And I’ll close by saying that if they try to argue that vastly greater amounts of protein are needed to maintain structure and function, I will have to hit the penalty button. I am 5’6” and I weigh 136 pounds. And frankly, I am more solid and muscular than most men my age, which is 60.  And I eat a plant-based diet that is practically vegan.  I eat no meat, no fish, and no dairy.  Occasionally, I eat a free-range, organic egg, but that’s it for animal food- and not every day.  Mainly I eat plants, including lots of fruits, vegetables, starches, and raw nuts.  I AM maintaining my structure and function, and they can't tell me otherwise. I don't claim to be the strongest man in the world, but if there is heavy furniture to move, don't worry, I can handle my end. If you can lift it, I can lift it.