Are we sure that there's nothing else going on with fertility rates? It seems odd to me that one of the primary drives of humanity has fallen off of a cliff so quickly. Sure, it mostly manifests as a drive to have sex and we can get around that with birth control, but that's not the only thing it does to us. There's a reason the concept of the "biological clock ticking" is a thing.
We know testosterone levels are dropping: "After controlling for confounders—including year of study, age, race, BMI, comorbidity status, alcohol and smoking use, and level of physical activity—total testosterone was lower among men in the later (2011-2016) versus earlier (1999-2000) cycles (P < 0.001). Mean total testosterone decreased from 1999-2000 (605.39 ng/dL), 2003-2004 (567.44 ng/dL), 2011-2012 (424.96 ng/dL), 2013-2014 (431.76 ng/dL), and 2015-2016 (451.22 ng/dL; all P < .0001)."
https://www.urologytimes.com/view/testosterone-levels-show-s...
Setting aside that semen quality is also affected... Maybe testosterone, or other hormones that might be affected by the same thing, also affect the drive to have children? It seems the more urban a civilization, the lower the birth rate.
When I just tried to look up if anyone has looked into that I couldn't find anything, but here's a nice overview of different theories on fertility rates dropping as a whole: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8977063/
We know testosterone levels are dropping: "After controlling for confounders—including year of study, age, race, BMI, comorbidity status, alcohol and smoking use, and level of physical activity—total testosterone was lower among men in the later (2011-2016) versus earlier (1999-2000) cycles (P < 0.001). Mean total testosterone decreased from 1999-2000 (605.39 ng/dL), 2003-2004 (567.44 ng/dL), 2011-2012 (424.96 ng/dL), 2013-2014 (431.76 ng/dL), and 2015-2016 (451.22 ng/dL; all P < .0001)."
https://www.urologytimes.com/view/testosterone-levels-show-s...
Setting aside that semen quality is also affected... Maybe testosterone, or other hormones that might be affected by the same thing, also affect the drive to have children? It seems the more urban a civilization, the lower the birth rate.
When I just tried to look up if anyone has looked into that I couldn't find anything, but here's a nice overview of different theories on fertility rates dropping as a whole: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8977063/