This makes sense. I could see that this helps social structures by testosterone levels making younger men want to look like a better prospective mate. Narcissistic tendencies are going to make males want to look better, acquire more resources and be more aggressive in pursuing mates. Once mating is accomplished, male testosterone levels drop probably so that they don’t attempt to mate with offspring and be better parents. I wonder if there is a causality in which testosterone levels drop in overpopulated areas, i.e. Japanese men having low testosterone levels and the growing population/age crisis there being caused by the high population density.

I can definitely say that it felt this way in my life. I have two daughters and no sons. My testosterone levels definitely dropped after they were born (I had blood tests taken). I’ve also mellowed considerably while becoming more generous and less vain, as friends and family will attest.