Human R_0 in state subjects and hunter-gatherers

tl;dr: State subjects are less healthy than hunter gatherers due to sedentarism, crowding, lack of diverse diet, etc. Child mortality is higher within the state, but the "basic reproductive number" still goes up, as females within states tend to reach sexual maturity faster, hit menopause later, and generally have regular periods (i.e. they are fertile more regularly and for longer.)

Despite general ill health and high infant and maternal mortality vis-a-vis hunters and gatherers, it turns out that sedentary agriculturalists also had unprecedentedly high rates of reproduction- enough to more than compensate for the also unprecedentedly high rates of mortality.

against-the-grainp. 113

Herman Pontzer's work with the Hadza sheds some light on this: they found that hunter-gatherers use no more energy in their active lifestyles than people with modern-day lifestyles generally do. * exploding-brain.gif * The working theory is that the body adjusts its own energy expenditure over time such that it falls within some narrow, "optimal" range, and so for those who are more active, things like reproductive or immune functions get a little suppressed (which is the normal and healthy state for Homo sapiens). Women tend to have less regular periods. People tend to have lower levels of estrogen and testosterone, which could explain the differences in timings of puberty and menopause, as well as the heightened rates of reproductive system cancers for the sedentary (more hormones => higher cancer risk). Other "modern" conditions due to inflammation could also be traced to an over-active immune system in the sedentary. 真的是吃饱饭没事做.


against-the-grain Scott, James C. 2017. Against the Grain: A Deep History of the Earliest States. ↩︎ 1