Thank you everyone who commented on my post around why people chose a low-carb high fat diet, and did they do so after a high-carb low-fat diet. Personally I could debate on just that thread for the next 10 years, and perhaps I will!
However it occurs to me a hypothesis following on from that question. Humans got to the top of the pile of the animal kingdom simply because their guts were so adaptable. So where meat was available they could thrive, and where plants were plentiful they could also thrive. (Please don't take this as me softening my stance on considering the WFPB HCLF lifestyle leading to the best long term outcomes...)
So if we look back at paleo, neolothic, 16th century, whatever times before that we want to study human kind survived. We recovered from the great plague, biblical plagues, the flooding of Noah's time. We somehow survived.
Is it down to our gut biome that enabled us to survive as almost carnivores where appropriate, and almost herbivores where also appropriate?
Survival is one thing. It means you have some continuity of being after an ice age perhaps! But when all animal species are thriving how do you get to the top of the pile?
There are those who argue that it is somehow the benefits of eating meat enabled human kind to so rise. There are others who argue that to so succeed you need the concentrated nutrition only available at its source - and that's the plant kingdom.
A possibly uncomfortable truth for someone like myself who advocates a vegan lifestyle is that the Blue Zones like Okinawa, actually ate some meat, possibly a small piece once per week. So these were not always entirely vegan communities. Of course there is a long-haul from a small piece of meat once a week to a daily "normal" sized modern slice of meat, but you get my point. The Okinawan's lived on sweet potatoes as the backbone of their diet.
So in this subject I am not asking how we all became so ill - which is largely down to the SAD diet easily and cheaply available in 99% of restaurants, takeaways and supermarkets, imo.
I am asking how is it that both men (the presumed hunters) and women and children not only survived but thrived. Is it a simple truth that the gut biome is so adaptable.
I'll give you one example of how the gut biome is adaptable for a High carb low fat diet. For a "normal" person the conversion of ALA to DHA/EPA maxes at say 2-5%. So many advocates of the low-carb community think HCLF people's brains will frazzle. Not so, because it turns out a benefit of a high-carb low fat lifestyle is that the conversion rate can rise to 40% which provides more than enough EPA/DHA to drive excellent brain health.
In the interest of balance, at the opposite end of the spectrum the almost complete carnivores ask a rhetorical question, where do they get their VitC from, since meat provides little or none.
There are lots of seeming paradoxes in the area of nutrition. If you have any other examples of how the human gut survives against the orthodox wisdom, this thread may not be a bad place to add a comment or two.