Lovebirds long thought to be monogamous are just better at sneaking around.
Females can activate their testes and deactivate their ovaries.
Have you ever stopped to wonder why sex and violence so often go hand in hand?
The results of Indiana University's National Survey of Sexual Health and Behavior provide an empirical look into Americans' sex lives.
In mammals, the sex of a baby is determined by the chromosomes it inherits from its parents. But, the combination an animal inherits can be quite different.
Sure, there are physical differences but outside of mammals, the terms "male" and "female" take on different meanings.
Did you know that there are fish out there that can change sex?
A study shows that men and women may have much different responses to stressful situations.
Were you allowed to watch R-rated movies as a kid? Do you smoke now? Learn about the link between smoking and R-rated movies on this Moment of Science.
Female aphids don't need males to reproduce. Their trick is called "parthenogenesis" and means big savings in time and energy.