I have actually long thought that fertility is a response to stress throughout nature and that, in humans, a low birth rate, as in Italy, for example, is evidence of stress-free living. It makes sense that reproduction would be triggered by an adverse environment because that increases the chance that natural variation would produce off-spring more in tune with the changed conditions. If so, then restricting a population’s dietary intake has the effect not of making them work harder, but of reproducing more off-spring.
Which means that the oft-repeated suggestion that the African rate of reproduction in North America was evidence of being well-provisioned is probably false. More like is that slaves and other immigrants reproduced in huge number because their existence was precarious and survival past childhood even more so.
Anyway, resistance is essential when liberty is being challenged.