I see a lot of speculation here about something like an unknown toxin being the cause. Is it possible that societal and cultural trends are driving this change

I see a lot of speculation here about something like an unknown toxin being the cause. Is it possible that societal and cultural trends are driving this change? In other words, the emotional quality of modern day life. Perhaps another explanation is simply just evolution. After all, what does physical prowess really get you nowadays compared with even 20 or 30 years before?