Comment on if the total fertility rate drops and stays below global replacement rate, will humans disappear?
iiGxC@slrpnk.net 4 months ago
The replacement rate isn’t static. It depends on both how many people exist and how many people are having babies and how many babies they’re having. If the total number of babies stays constant, then whether it’s below or above the replacement rate depends on the size of the population. So for a hyper simplified example, if 100 babies are born per yer, that’s below replacement for a population of 110, but above replacement for a population of 90, but overall the population size will trend towards 100. Obviously real life is way more complicated, but even if the birth rate is low now, it’s far more likely we’re just moving towards a different population size, not a population of zero
notsofunnycomment@mander.xyz 4 months ago
Expressed as “the average number of babies that an individual woman needs to have for a certain population to stay the same size”, the replacement rate should not depend on population size, right?
If you express it as an absolute number (e.g. number of babies per year) than obviously it will depend on population size.
From what I understand, the replacement rate (expressed as the average number of babies that an individual woman needs to have for a certain population to stay the same size), depends mostly on what percentage of people die before they (can) have babies.