>>509203479 (OP)testosterone alone doesn't mean much - the receptors themselves also vary among people and ethnic groups
if I have a testosterone level of 200ng/dl, but I'm 6 foot 8 with a 10 inch cock and 4 girlfriends, then it doesn't fucking matter
testosterone levels also drop with age and poor health - countries with younger populations will naturally have higher levels, but it has no sway on young people in old countries
there are better metrics to test for masculinity and health
examples are average stature, average muscle mass percentage, average body fat percentage, percentage of overweight adolescents
look for functional testable values, not for random numbers
as far as global populations go, sperm counts are dropping *everywhere*
https://doi.org/10.1093/humupd/dmac035