Billy wrote:
Doug Freyburger wrote:

About 5
million years ago we went from tree dwelling apes with a high percentage
of fruit for calories through a transition to the peak predator on the
planet spread somewhere across that next 5 million years, to a herding
species under 50K years ago who ate a much less varied list of prey
animals to a farming species under 20K years ago who ate far more grain
than was good for us, to an industrial junk food species in the last
couple of centuries. Since it takes around 5 million years of steady
diet to evolve it to optimal and humans have not had that, humans don't
have any optimal diet. But the closest we have to it is hunter gatherer
cultures who eat varied lean hunted meats, who walk several hours per
day and who eat wildly varying plant foods across the year.

I've read many accounts that hunter gatherers spent less than 20 hr./wk
in foraging food. I'm sure some spent more. Some spent less.

I remember the same from my lower division undergraduate anthropolgy
courses. It didn't account for the several hours walked per day. Much
of that walking is the result of nomadic movements.

The book NeanderThin by Ray Audette is one of several books on
paleolithic dieting. In it he suggests an exercise program that mimics
a hunter gatherer exercise program. Some days have long walks, others
intense games all in a time frame long enough that the body does not
settle into a routine. He suggests falconry as a good hobby, too. That
sounds like fun/

Where does this 50K for herding come from? It's news to me.

It's a wild extrapolation on my part based on estimates that dogs may
have started their domestication process longer ago than that, on
extinctions spanning anywhere from that long ago to more recent than the
glacier retreats, on the degree of domestication suggested by the furs
worn by "Otsi the iceman". It's not hard to find suggestions that
animal husbandry is a lot older than plant argiculture so I got very
aggressive in a guees.

10K ago is the usual
number given for the beginning of agriculture.

But it might have been as far back as 20K in a few regions of the world.
And animal husbandry is an unknown amount older.

The industrial revolution
started about 300 years ago, but junk food made from ubiquitous white,
wheat flour is only about a century old and only wide spread in the last
50 years.

It's the evolutionary source for a claim that certain of the highest
sugar fruits aren't beneficial in this thread.