Declines in sperm counts and testosterone levels over the last 20-30 years may not be fully explained by cell phone use due to the recent widespread adoption of smartphones.

“And so it's hard to explain all of those declines simply on the basis of cell phone use. There's some interesting effects of hormones that actually you can observe on the outside of people, that tell you something about not just their level of hormones, but also about their underlying genetics. And these relate to beard growth and baldness. And it's fascinating. The molecule, the hormone dihydrotestosterone, made from testosterone, is the hormone primarily responsible for facial hair, for beard growth. As”