The parent comment both says that this is a global phenomenon and links to a study (not on Americans) whose _abstract_ says "There was a highly significant age-

The parent comment both says that this is a global phenomenon and links to a study (not on Americans) whose _abstract_ says "There was a highly significant age-independent decline in total testosterone in the first and second decades of the twenty-first century. The decline was unlikely to be explained by increasing rates of obesity".