"and the kids had to dive in to help out the second they could lift something heavier than a couple pounds"
Earlier. Picking berries, seeds or ears of grain is something very small hands can do.
"We forget so easily that for the entire history of our species - up until just recently - simply staying alive and somewhat warm and minimally fed was a hundred-hour-a-week job for mom and dad."
But no. You are talking about a primitive (poor) agrarian society. That only started a couple of thousands years ago, while our species used fire since over a million years in a semi nomadic live style. And those tribes in good territory, they did not had so much back braking work, as long as big land animals were around. (Also, hearding cattle was for the most part a very chilled job as well, but that also started rather recent)
Earlier. Picking berries, seeds or ears of grain is something very small hands can do.
"We forget so easily that for the entire history of our species - up until just recently - simply staying alive and somewhat warm and minimally fed was a hundred-hour-a-week job for mom and dad."
But no. You are talking about a primitive (poor) agrarian society. That only started a couple of thousands years ago, while our species used fire since over a million years in a semi nomadic live style. And those tribes in good territory, they did not had so much back braking work, as long as big land animals were around. (Also, hearding cattle was for the most part a very chilled job as well, but that also started rather recent)