I agree.

However, natural selection is not a perfect process, as we find with numerous examples. It manages with a series of local optima, and does not fine tune anything beyond that. There are so many examples of faulty or really klug-y designs which clearly indicate this.

So, the assumption that, if we follow what our ancestors ate as hunter gatherers, we will be in perfect health, is, in my opinion, rather faulty. I know that paleo folks don't explicitly state this (faulty) assumption, but its implicit in most of their talk/writing.
Natural selection is not perfection. Following a perfect paleo diet (if one exists, and if we found out exactly what it was) may not rid us of all/most diseases or keep us in good health and cheer always.

Its true that if we significantly deviated from it, we will suffer, because our body would not have evolved to cope with too many deviations, and there is evidence for that. However, not deviating will not in any way ensure that we wont have health issues. The human body is too imperfect and klugy a contraption for that.

Its worth reading Gary Marcus' Kluge. Gives wonderful perspective.

Well, you might just be right Shobha. But I prefer to believe the observations of Weston Price in his book Nutrition and Physical Degeneration. Our genes might be programmed to build us crooked from the start, but from a natural selection perspective, that doesn't make sense.

Natural selection does not allow the crooked to reproduce. It only allows the perfectly suited to reproduce. Perfectly suited for what? Perfectly suited for the hardships that killed off everybody else. That's exactly what natural selection is.

Who would live without modern medicine? Those who ate a diet that kept them healthy. What kind of diet is that? Well, natural selection dictates that whatever diet our ancestors ate to live through the hardships must be adequate for us today. However, we don't actually know what kind of diet that is because nobody from that time is here to tell us. We have clues in their bones and such though. Our only way to be sure is to eat something today and see if it makes us sick. If it makes us sick today, obviously our ancestors did not eat anything like that then.

Obviously, a significant diet change is one such hardship which our species must have adapted to in order for us to be here today. Obviously, a high carb (read: lots of plants) diet is not what we had to adapt to.

Maybe natural selection is not a perfect process. Maybe it allowed some crooked individuals to live and reproduce. And maybe some of us today are their descendants. But the odds are that anybody who is crooked today, is so due to inadequate materials (i.e. diet), not to inadequate genes. After all, genes are made of stuff, and that stuff comes from diet.

Hey Martin.

Well, I agree that deviating away from the kind of nutrients we ate for most of our evolutionary history does screw up our system - no disagreements at all there.

However, I dont think that merely sticking to what our ancestors ate will result in perfect health (no thats not a strawman, many paleo folks have that unwritten law, although they may disagree on what a strictly paleo diet is). It certainly will improve our healths manifold. But health problems will still remain. Evolution does not aim for perfection. Is low carb the best available currently ? Probably, yes. But thats about it.

You dont need to be perfect to be successful in natural selection. You just need to be better than all other alternatives currently in existence. Local optima. If one species of predator ran faster than another, it would catch more prey. If your alimentary canal could digest some plant matter, thats enough to tide you through lean times. You dont have to do it perfectly.

Look at how the optic nerve is connected to our eye for eg. Or our appendix. Look at how imperfect our thinking is.
Lots of design imperfections everywhere. Why should nutrition and health be an exception ? It isn't.

And even though modern medicine (scientific medicine) has a lot of imperfections today - those are not because of any fault in the scientific method. Improved hygiene, antibiotics and life saving surgery are definite improvements for humanity.

Along the way, the drug industry, food industry and government started colluding (implicitly or explicitly) to improve their profits and science suffered because of that. But that does not mean we pooh-pooh all of modern medicine and start ancestor worship.

We have to improve on what our ancestors did. Because knowledge is cumulative.

Yeah, it's not about paleo food reenactment, it's about paleo metabolism.

Patrick

Shobha, let's take your example of the predator that uses his speed to catch his prey. At first, the predator can catch his prey easily. Or at least, he can catch the slowest prey easily. What's left is the fastest prey of the lot. So the predator wants to catch his prey again but finds it's now faster. So he must become faster as well. From the lot of predators, only the fastest can catch the faster prey. But again, only the slower prey gets caught. What remains is ever faster prey. And what must catch those prey is ever faster predator. Do this for millions of years and we end up with extremely fast prey and extremely fast predators.

In this world, there is no place for the weak or sick or fat or stupid. Even just a little. Because we're not talking about a little faster predators, we're talking about extremely fast predators. The elite. The best of the best. Selected through millions of years of hunting down ever faster prey. Well, this same mechanism of natural selection also applies to us. Only the best of the best survived.

Until we introduced modern medicine.

Have you seen the movie "Idiocracy"?

Patrick

Yes, very funny movie. But that kind of future is highly improbable. First, because stupidity is a self-correcting problem. Remember the bit on the news about the guy who looked down into a fireworks tube? He got his head blown off. Well, he ain't gonna make stupider children. Remember every bit of news that talked about guys going off on a rampage killing other people right left and center? Well, they died too and they ain't gonna make stupider children either. Even today, natural selection still exerts its power.

There's the idea of "smart enough". We're now smart enough to reproduce even though we are fat, sick, weak and stupid. Yeah, I know it's kinda contradictory to be both stupid and smart at the same time. However, we can be smart in one domain, and stupid in another. This is possible because we now specialize. So, we're smart enough to be able to reproduce even though we're fat, sick, weak and stupid. But we're too stupid to realize that what's making us fat, sick, weak and stupid is our belief that sugar is food.

I would replace the word "stupid" with the word "ignorant". It's not that most cannot know (as in stupid), it's just that most don't know (as in ignorant).

Patrick

Well, maybe we're just ignorant. But it doesn't matter because sugar kills us anyway. And again, natural selection will select in favor of those who can handle sugar or those who can avoid it.

Can't claim to have gotten fatter on "zero" carb, because the lowest I've been able to get my carbs for extended periods of time is about 10-15 grams because I eat a little cheese here and there, and also like liver once a week. But that's a drop in the bucket compared to amount of carbs manufactured by the body (which is 100-150 or so grams via gluconeogenesis) so I don't seen why it matters. And I've definitely put on fat at that level, maybe 10-15 pounds.

And my dogs, two of whom have always been on a "zero" carb have gotten fat (the smaller ones have definitely gotten obese) even though they were not fat to begin with.

I've been wondering lately (largely while in la la land, but I think the idea is worth considering) whether nutrient selection belongs in this whole argument? Diabetic rats self-select high fat diets, Taubes writes about rats that can't secrete aldosterone drinking salt water at such a rate that their sodium status is good enough to keep them healthy, etc. The rats don't seem to need to adapt to this sort of thing, it seems to be built right into the system to start with.

Even on a zero carb diet, should some of the protein and fat be consumed separately, so that our natural appetite can balance itself, just like in the rats?

(I realize that some people have excessive cravings for sugar, but I would suggest that this is probably a false appetite caused by something else that would increase in the system as a result of eating sugar.)

Well, that's basically the difference between instinctive behavior and acquired behavior. We do have some instinctive behavior, the reflex to grasp with our hands and to suck tit. It's only useful for a few years though. The rest is all pretty much acquired. Indeed, I think that what makes us human is our innate ability to learn and our obvious lack of instinctive behavior. Our brain is huge and it can learn a lot. But paradoxically, it can't hold even the simplest of instinct which is the proper choice of food.

I'd like to know where you came up with the figure of 100-150gm of carbs via GNG. That would mean you have to consume 250gm of protein in a day IF GNG converts at 60% efficiency, which isn't even proven

But even if that's true, it can't be compared apples to apples to dietary carbohydrate consumption. It's not the same thing

Furthermore, there's no reason for the body to convert any of that protein into glucose via GNG since it's been proven in this study that the brain doesn't need glucose during fasting, and since a meat/fat diet is metabolically the same as fasting, it would make sense that the brain wouldn't need glucose on one either. Also, there are toxic byproducts to gluconeogenesis, and since the body doesn't need it, why would it convert protein if it doesn't have to?

It seems we're able to download that book from this link for free:
http://www.archive.org/details/stud...onged00beneuoft

I think before considering whether "anybody" has ever gained weight on any kind of eating plan, You gotta consider that women and hormones seem to have a specially dysfunctional relationship. Amory was eating 1200 calories of nearly all fat and a little protein and working out hard enough almost daily to make Jillian look like a wimpy little whiner, and she gained 30# in a ridiculously short time. -- for Hormonal reasons. That kind of thing kinda has to be ruled out as a possibility before a weight gain can validate or incriminate any eating plan.