> Life expectancy at birth is a pretty good proxy for how physically healthy people are in general [...] (Note also that improvements to life expectancy at birth are not entirely due to falling rates of childhood mortality: see here.)
Not entirely but it is enough of a factor that naively comparing life-expectancy stats without accounting for it is probably a bad idea.
IMO infant mortality improvements underlie so much of the demographic changes involved in a country's industrialization, economic development, and then cultural shifts.
Skeletal records also suggest higher levels of health vs post-agriculture, IIUC. (Although it's pretty hard to be confident about much from such a long time ago, of course.)
I think part of the mechanism is that sickly hunter-gatherers die and do so early-ish, but agricultural societies can keep those people around.
Also if you have too many hunter gatherers around for a given area (and assuming they can't leave), some of them will die within perhaps a few years of starvation.
There's a much wider band of population densities for agricultural societies where they can produce enough calories to keep people from starving, but many will be miserable from malnutrition.
As an aside: in our over-populated hunter-gatherer scenario the average amount of food available might still be plenty, but there might be the occasional bottleneck during the harshest parts of winter.
Thanks to that bottleneck keeping numbers low, the typical day of life experience for your typical hunter-gatherer might be pretty nice. And thus you can get 70+ healthy years for many of them.
>some of them will die within perhaps a few years of starvation.
We can be fairly sure that before a group of humans die of starvation, they die of violence. Either from another desperate band of humans also starving, or trying to take those humans' land. This is certainly the pattern for hunter-gatherers living on marginal land in the last millennium. Presumably, this was also the case when they were hunter gatherers on prime land too - before they were forced out of it by more numerous, and better organized, agriculturalists.
There's no _good_ way of ever going back to a hunter-gatherer society, unless you want to kill 99/100 people (or tell those 99 they can never have children - and enforce it through child murder or sterilization). There's no _good_ way of going back to a pre-industrial society, unless you want to kill/sterilize 9 out of 10 people. Not saying you suggested these - but it should be pointed out.
> We can be fairly sure that before a group of humans die of starvation, they die of violence.
I'm not completely sure about that, but that doesn't alter the argument in my comment. It's just that violence would be the short-term trigger of their death, with a lack of calories being the underlying cause.
I know it's anecdotal but my grand-parents lived 80+ and my grand-mothers had only half the kids they gave birth to. Also trying to squeeze 2-3 more years out of a 80 year old is torture.
That's not to say that medicine didn't improve and it's genial. I do certainly like my spectacles and diabetes medicine is life changing for the people affected. But the measure of life expectancy is crap. A better measure should be comfort/pain during your 70 years.
Not entirely but it is enough of a factor that naively comparing life-expectancy stats without accounting for it is probably a bad idea.
IMO infant mortality improvements underlie so much of the demographic changes involved in a country's industrialization, economic development, and then cultural shifts.