I've vaguely described what a paleo diet is. What I haven't gone over are the arguments for adopting it.

First, the facts. Humans have only had agriculture for the last ten or twelve thousand years. Before that all humans were hunter gatherers and had been for hundreds of thousands of years. We hunted (actually, early humans hunted all the large mammals on earth into extinction), gathered vegetables and fruits and grasses and nuts and eggs that grew wild. No cultivated grains - what we know as wheat didn't exist until early farmers cultivated crops for a long while and bred grasses that provided more food.

None of this so far is controversial. A few morons out there think our paleolithic ancestors were vegetarian, but there's just no way to support a human body by foraging on vegetables alone. Primates that don't eat meat have to eat all day long. They have bigger stomachs, smaller brains, and can digest a lot of plants that we can't digest. The only way to support a large, calorie hungry brain is by eating meat.

By the way, lots of groups of people maintained this hunter gatherer lifestyle until very recently, and a few groups still do it in very isolated areas.

Now, what happened when these people started growing crops instead of hunting for their food? Well, they got sicker. Their kids were shorter, had crooked teeth, and developed all kinds of debilitating diseases that had never occurred before. We can tell this by looking at and comparing the remains of early agricultural people to their hunter gatherer ancestors. Those easy to grow grains have too many carbohydrates, too many anti-nutrients (substances that bind to and leach nutrients out of your body), too little protein, and too few other nutrients to support healthy humans.

So why did they stick to it? It's all about population density. Once you have enough people in a given area, say a valley, it's a lot easier to feed them all reliably with agriculture than through foraging. And if your neighbors are foraging and you're growing food, you can support more kids, even if their teeth are crooked and they get arthritis when they age. More kids means more fighters, and pretty soon your neighbors are growing their own crops to keep you from killing the males and stealing their women. Agriculture gives an advantage to your group, and pretty soon every group of humans who weren't isolated had to start doing it. They also domesticated animals, which helps you get your farm work done, and so we got civilization.

The crux of the problem is that we were well adapted to being hunter gatherers. What does that mean? It means all humans had a complement of genes that made them healthy on a hunter gatherer diet. Over a couple of million years any humans who couldn't, for example, tolerate meat well, would have either died before passing on their genes or just had problems breeding (they would have been less healthy, and have attracted fewer mating opportunities). Remember, these people lived in a harsh, violent environment. Nobody was going to put perennially sick members of their tribe (members who couldn't tolerate their diet) into hospitals or nurse them for decades and certainly nobody was going to bear their children. Over hundreds of thousands of years of not being passed on, non-meat-friendly genes would have disappeared from the gene pool.

Back to the farmers. Once humans started farming and raising animals, a new set of genes was going to be advantageous. For example, suppose some kid is born with a mutation that allows him to digest lactose as an adult. If that kid is born into a hunter gatherer society, there's no particular benefit for that kid - nobody has access to milk, so that kid wouldn't come across as a good catch or anything. Now suppose that same kid is born into a group of farmers that has some cows around. The kids drink milk, but the adults can't handle it. Except for the mutant, who keeps on drinking milk, because he can (remember, he's got the gene that lets him). No big deal until, maybe one year the crops fail. All the other males are starving, but this one guy is healthy and strong from drinking milk. Who do you think is going to get laid more often (excuse my vulgar way of putting it)? After a few generations you have a population that can tolerate milk better than their ancestors.

In fact, you can see this - lactose intolerance is prevalent among groups that didn't domesticate cows, while those that domesticated cows early (relatively speaking) have much less lactose intolerance. It takes time, though, for these changes to occur - many thousands of years - because you have to wait for the right mutation to occur, then spread, etc.

Suppose some alternate world where humans lived on grains and dairy for a million years. I'd guess that we'd be well adapted to, and live healthily on, those grains. Someone somewhere would have gotten a mutant gene that lets them expel or neutralize phytic acid, and they would have had stronger, straighter teeth, and in ten thousand years all humans would have that gene. Someone somewhere would have gotten the set of mutations that allows their immune system to handle milk proteins and passed it on.

But it hasn't been a million years. I'ts been ten thousand, and while we've partially adapted to the agricultural diet, we haven't fully adapted. How do I know? There's lot of evidence that grain and dairy cause all kind of health problems that we don't get from meat, fruits and vegetables, and seeds and nuts.

Does that mean anything modern is bad to eat? I'm going to say not necessarily. Take tea, for example, Did paleolithic humans drink tea? I don't think so (I could be wrong, though.) Does that in itself make tea bad? Well, it might be that tea has nothing in it that is particularly bad for you, despite the fact that we didn't evolve to be tea drinkers.

The facts about our evolution, though, should give us an idea of what to look out for - of what we should be suspicious. If our paleolithic ancestors ate it, then we're adapted to it. If they didn't then we should be SUSPICIOUS - we should look at the research and see if it's okay or not.

I'm guessing that grains and dairy act as sort of low level allergens for a lot of people. I don't get an asthma attack from eating a bagel, but eating bagels might make the asthma attacks I do get, triggered by other allergens, more severe. I'm hoping that taking grains and dairy out of my diet for a few weeks or months will give me more energy by relieving some of my allergy symptoms.

What makes me think that this might work? Two things. First, it makes evolutionary sense that I wouldn't be well adapted to the proteins in grain and dairy. Second, there's lots of anecdotal evidence that people who take grains and dairy out of their diet feel better - more alert, less tired, etc. Anecdotal evidence is NOT PROOF. I'm not sure about this. I have just enough evidence to think it might be true and try the diet out.

I'll let you know if it works.

Osu.