Paleo is optimized for reproductive success/survival
Successful/optimalreproductive survival does not equal or entail health or health span This is NOT about longevity, --a red herring in the present context.
Paleo may give you ideas, but given 1 and 2 above, for health(span) there is no reason to directly imitate it. (Anything is better than SAD, of course, --again a red herring)
Features that promote reproductive survival may be (a) neutral) (b) beneficial (c) harmful for (postreproductive) health(span)
(At least in post-reproductive life) you clearly want to actively avoid those aspects of the paleo metabolic environment that fall under (c), --assuming you can identify them.
Quite some research has suggested high protein intake as falling under (c)
You might argue that optimizing for reproductive success is not just potentially (which I think cannot be reasonably denied) but typically deleterious for health(span).
Kulimai (actually that's me again (sorry) wherever a google account is required) argues on Don's Primal Wisdom like this: "A rather imperfect metaphor that nevertheless indicates what I have in mind: Suppose if your car finishes top 2% in a killing race that you must participate in, your car is likely to be total junk by the end but you definitely get a shining new replacement. If the car finishes top 10% your old car may still work for a number of years (good also for spares) but your chances of getting a replacement are much reduced. You may choose either strategy. But if these races are repeated many times over a longer time span eventually only owners with the first, more agressive strategy will continue to have cars. The kind that put the special fuel in the tank that makes the car go twice as fast for the first few hundred miles without regard to whether it cripples the engine soon afterwards..."
Now the reason for the title at last: Whenever KGH points out that our ancestors ate a lot of fat I get uneasy, --maybe then current science is on the wrong track and high fat is like high protein in relevant respects ( ie. good for reproductive survival of the genes but bad for the health(span) of the individual?) But with Don's research and when Stephan G says "I think most of our ancestors have probably been eating more carb than fat for a very long time", I'm reassured that a high fat diet has a good chance of being healthier than a high carb one.
Reproductive survival and health(span) seems to be largely a growth vs repair orientation issue. High carbs, high protein appear to stimulate insulin, IGF-1, mTOR, --growth, not repair.
I think you need to re-think your fundamental delineation between long term survival and reproductive success. They are, in fact, one and the same when it comes to humans. You cannot successfully reproduce without being alive long enough to protect and teach your children how to survive, something which will take you the better part of your adult life. Human tool use and culture are fundamental survival strategies which rely entirely on the existence of elders to pass on knowledge to the next generation.
Even basic physical post-birth development is so slow as to require longevity on the part of those who have already reproduced. We are not mayflies or fish; we can't just spray some sperm and eggs around and have 10% of them grow to adulthood. Applying evolutionary thinking predicated on such logic to humans just doesn't work.
Also, I'm unaware of KGH making any recommendation "because our ancestors" did anything. He's repeatedly stated that such logic can only generate ideas which must be validated with actual science. He's pretty strongly stated that you shouldn't do certain things "because our ancestors didn't do them", but you've not mentioned that anywhere. There's no macro-nutrient recommendation in the "don't do" list.
From what i'm reading, your whole answer is predicated on the assumption that paleos are following this diet as some form of reenactment, as kgh calls it, and it's not until your tenth point when you actually inject specific scientific reference into your argument. You may be right or you may be wrong, however, from my experience with my own health and the health of friends and family, I'm following a paleo diet(which sometimes gets in the territory of high fat or high protein) because it makes me feel better, makes my health markers look better and makes life an overall more enjoyable experience. That argument over reenactment and macronutrients is something that has and continues to be argued over by bloggers and laymen alike and will continue to be but you will find most here don't fall under that category.
"1. Paleo is optimized for reproductive success/survival"
I have to disagree with that on historical grounds. Neolithic/agriculture all but wiped out hunter gatherers across the globe, due to their much increased reproductive success.
Thanks to all for the reactions. Notice that in points 1-3 I'm saying more or less exactly what KGH says: that paleo re-enactment is not a good idea. But then KGH also points out that just because something is neolithic it does not follow that it is poisonous and in the next three points (4-6) I am saying that just because something is paleo it does not follow that it is good for one's health(span). And in further three points (7-9) I give some reasons to think that in fact aspects of paleo diet that are not optimal for health(span) are very likely to be not untypical.
Then in point 10 I hinted at a potential alternative paradigm
Pfw correctly notes that there may be selection for longevity, especially in the context of humans with extended childhood ("the grandparent effect"). No doubt having knowledgeable and helpful elders around might confer an evolutionary advantage. The trouble is, we do not know how much, and whether other evolutionary pressures (like for example competition for resources) override this. So even granted the existence of the grandparent effect, its force is unclear.
My point about evolution selecting for survival of those who are optimized to be successful at reproductive survival is of a quite different nature: it is trivially true given an evolutionary approach. In fact this point is just a way of stating the central survival of the fittest hypothesis.
So I don't think I owe any further arguments here, I am only pointing out implications of certain truisms of the evolutionary approach. Notice further that I am not saying anything like that a paleo diet is unhealthy, all I am saying is that paleo is not a guarantee of being good for health(span) and aspects of paleo may easily be outright harmful for it. This clearly follows from what I am saying quite independently of what weight one assigns to the grandparent effect. And no, this does not mean that SAD crap is better...
I may of course be completely wrong. But overall the reaction of this community to my question has been comparable to that of an establishment MD to questioning the diet-heart hypothesis. "Ignore the awkward"!
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