Though it can be difficult to tease out the causes of broad demographic trends , knowlton 's work was instrumental in spreading what one historian has called " the good news that sex and procreation could be separated . "
The suggestion of dr hatemi and dr mcdermott is that political action is the collective expression of some pretty primal biological motives : those of survival and procreation .
The compromise position that the church adopted was that sex was proper as long as it was oriented toward its proper function , which , the church held , was procreation within marriage .
And where tombstones might stand , declaring pious hope for some god 's mercy in the afterlife , their cemetery sports instead a vigorous forest of phallic symbols , signaling an intense interest in the pleasures or utility of procreation .