I am student of the paleo science and lifestyle and read pretty much everything I come across. When people begun to harvest they become shorter, died sooner and so on. True!
But once again, cause and correlation...
Could it be that people become shorter since they were not travelers any longer? Could it be that they died sooner since they were living in villages with more people and thus got sick more often from their neighbors and animals?
So far I have seen no one mentioning these facts.
I am still very interested in paleo and believe we shouldn't eat all this artificially manipulated crap we eat but the ruling about paleo is still out there.
[Edit: I see that people haven't been answering my questions but I lot of other stuff. What a waste of what I see as a genuinely important question. However, with only 1 upvote for my question it seems that the interest is very low.]
Obviously there a dozens of theories and there is no possible way to truly get to causal relationships.
Do I think that farmers who ate corn and started to harvest wheat suddenly got fat and died from an unhealthy diet? No. Do I think that the movement to an agricultural society was optimal for health? No. Do I think the obesity epidemic is solely based on agriculture? No....
My opinion is that the obesity epidemic is a confluence of four events.
Modern medicine also saw huge gains during this time frame, this led to medicine masking the effect of these events on health -- Sure we are using hydrogenated oil, but look people are living longer, etc.
However, now that we have the benefit of hindsight we can see how these incremental changes to the diet have actually been very problematic. We also see an environment where mass manufactured foods are literally EVERYWHERE. But, if we take a step back and consider our biology we quickly realize that humans were just not made to eat this way. And even with 10,000 years of agriculture we have not evolved or adapted very well to eat this way -- primarily because we created a culture where sick people (obese, asthma, genetic disorders, whatever) can thrive. This is a major accomplishment of mankind. We do not just dispose of the weak, we create an environment where everyone can thrive. Complicating this, the effect of eating SAD is not seen in most people until after procreation stages (i.e. late 20s early 30s -- yes people procreate past that, but you know the point). The side effect of that is that natural adaptation (in the Darwinian sense) will not remove these traits from the gene pool.
So given the luxury of hindsight, we have realized that there is a biologically optimal way of eating. We have yet to find a blood test (although we are close) that can reliably tell us how were are genetically designed to eat. But we can use human evolution as a guide. For me that means lots of veggies (including tubers and roots), some meat, some fruits, and some seeds.
Personally, I do not marry myself to the dogma of recreation -- that is, only eat what our paleolithic ancestors ate -- because (1) It is impossible to eat that way (the fruits, veggies, and protein sources are not available today; (2) I believe I have continued to evolve so there are things my body is better at eating today; (3) Which ancestors? I'm not a purebred; and (4) I don't find dogma or prescriptive statements to ever hold true.
I think about how Empires are always grain based, From Egypt to the Roman to China to the USA. Grains are a cheap way of feeding lots of people in an overpopulated, resource impacted society. So I ask myself why were so many people needed? To wage war, maintain Empire and acquire more resources. This is just speculation but I think it holds up, not gonna write a thesis on this topic.
I'm with CD on this one...my concerns are far more modern. I will just add a few more points:
In the 70s is also when older wheats were replaced by modern dwarf hybrids, which totally changed the gluten & nutritional profile of wheat. Witness the rise of celiac & other inflammatory disease.
More recently, traditional fats were replaced by industrial seed oils.
Finally, and a bit later, the low fat craze made many of us start eating way more carb (and thus way more modern dwarf hybrid wheat), less meat, less fats.
And then there's the modern industrial meat industry.
I don't worry about whether or not my diet is historically accurate. I don't even worry about paleo "rules". I eat a modified paleo/WAPF/primal diet that has allowed me to lose the weight I wanted without having to go to bed hungry. It has also made me more energetic and less prone to illness. It has improved my skin, hair, nails & teeth, and totally taken care of the early stages of arthritis I was experiencing.
If it turned out that all the evolutionary basis of the paleo diet was just plain wrong, I'd go right on eating what I'm eating.
It's not that much of a mystery. Certain plants evolved mechanisms against predators that would eat them. The predators, in turn, developed mechanisms to cope with those defenses.
Since a plant cannot get up and run, it can either make itself difficult to eat, using thorns, or other mechanically useful alterations, or it can evolve to taste bad, or contain toxins and anti nutrients that harm the predator.
The keyword there is harm. These classes of plants evolved to selfishly propagate their own species and avoid being eaten. Humans can eat them, but at a price. That price is shorter statute, tooth decay, shorter lives, autoimmune disease, atherosclerosis, and so forth.
As a simple example: good luck trying to prove that living in close quarters with other humans would have caused dental carries. There's only one thing that does that, which is a specific genus of bacteria, and that bacteria doesn't thrive when you eat meat.
Other plants developed in a different pathway, they evolved to attract insects to germinate via pollen and flowers, and produced fruit to encourage mammals to eat them, and carry their seeds further away.
Animals can run, hide, bite, claw, burrow, to escape predation, so they're less likely to need poison, though some, have infact developed venom. We don't tend to predate those that can kill us with venom, we tend to predate those that are less capable of defense.
I would also suppose that if you were to remove all modern fakery in foods, you'll find that we are evolved to find those foods that are healthy for us to be the same that are tasty. If you go back to a time before pollution, eating fresh fish, mollusks, and shellfish is perfectly safe, eating lots of cooked wild boar is perfectly safe, etc.
You weren't likely to eat oxidized fish oil because to us it smells terrible, and it does so as a signal to prevent us from eating possibly harmful things.
On the other hand, grains were very difficult to harvest and left you prone to roving bands of marauders since you were more likely to stay on your land than starve, thus leading to slave labor, taxes, slavery, and governments. These brought with them higher density populations, sure, , but people could usually run off into the woods and start new lives fairly easily so long as water and fauna were plentiful - but the investment of work into land is what mostly kept them there. It was easier to put up with the taxes of roving bandits who eventually declared themselves ordained by this or that god as king, than give up their grain xenomorphine addiction, and thus delegated themselves to serfdom.
We can even see the effects of grains on our pets. Both cats and dogs are obligate carnivores, when fed their naturally evolved diet of meat, they thrive and live long, healthy lives. When fed dry food which usually has gluten as one of the first ingredients, if not the very first, and then has rice, or corn as the next, live short, painful lives with plenty of diseases that are analogous to what we see in ourselves, when we eat the SAD.