Some viruses can hide out in the body and reemerge at later times. Which viruses do this, and can the new coronavirus do this too?
Disorders affecting penis development are among the most common birth defects seen in humans, and rates are on the rise.
There are many cultural and social factors involved in making a baby into a man or a woman. But biologically speaking, sex starts when you're just a tiny group of cells in your mother's uterus.
We have the penis of a monogamous primate yet our body sizes suggest our ancestors slept around a lot.
Men with Klinefelter’s syndrome are infertile, as the extra X chromosome affects the ability to produce sperm.