I can't think of a more reliable source than testosteronedecline.com
LinkedinLunatics
A place to post ridiculous posts from linkedIn.com
(Full transparency.. a mod for this sub happens to work there.. but that doesn't influence his moderation or laughter at a lot of posts.)
From the website:
The truth is that [the] whole project is (most of the time) quite inaccurate and error-prone, and often involves way too little data to really make a judgment, despite my best efforts. It also involves my amateur method of “age-adjusting” the results to be comparable. So this whole project is quite inaccurate and shouldn’t be used for serious conclusions. But if you understand the inaccuracies involved, you still may find it interesting.
“Listen, we know we’re full of shit, but that won’t stop your anti-trans uncle from posting our nonsense on Facebook.”
A useful approximation of normal T levels in humans can be seen in present day hunter gatherers in Africa. The Hadza tribe was shown to have an average level of 151pmol/l, well below that of what we see in societies such as America. We can, therefore, argue that the reduction of T levels in modern man over the last few years is a shift back towards the norm.
That face when high testosterone turns out to be caused by lead in petrol.