This experimental study used life-sized and screen-based 3D male avatars to test how penis size, height, and body shape ...

"Size matters" sounds like a tabloid cliché, but for evolutionary biologists the size of the human penis is truly a puzzle.

If you have ever been concerned about your penis size, you're not alone. The size of the male sex organ has long been thought to be an indicator of a person's testosterone levels and sexual abilities.

Men assess potential rivals that have a larger penis as more of a threat, both physically and sexually, according to a study by Upama Aich at the University of Western Australia and colleagues, ...