Gonadal hormones like testosterone and estrogen play a major role in activating and maintaining libido (sexual desire) in both men and women. The influence of these hormones changes with age, and central (brain) factors become more important over time.
Selective mutism is a real thing. It's an involuntary anxious response, meaning most of the times the person WANTS to speak but cant! In relaxed situations they can even be super chatty!
Almost all frogs fertilize the eggs outside of the female's body. The male holds the female around the waist in a mating hug called amplexus. He fertilizes the eggs as the female lays them.
