> Fertility rates, at a constant level, are brutally exponential systems which do not 'slow down'. If fertility rates are correlated to your ancestor's fertili

> Fertility rates, at a constant level, are brutally exponential systems which do not 'slow down'. If fertility rates are correlated to your ancestor's fertility rates, then a decline can "slow down" just because the remaining people of fertile age will be disproportionately from families with higher fertility rates.