While it is rather the norm for this piece to scour scientific journals on the theme of testosterone, and bring the best to your notice, this time it is somewhat unusual. For the journal in question is the Journal of Avian Biology!

Researchers have found that male songbirds, as response to habitat loss due to wildfires, failed to molt into their ornamental plumage as they used to. The result: they became less attractive to potential female mates!

And indeed they had lower testosterone, which is of course related to the showy feathers. Not unlike testosterone's linkage to facial hair, one thought, and decrease in beard growth in men is only one of the signs that a man's testosterone level is low. For the other signs, you can take the quick quiz below, and not only get your score on various parameters, but also index them to other men who have taken the quiz. And it takes less than four minutes to complete!