Sex

Polar bear sex involves long-distance tracking, fierce battles and lengthy copulation.

Dung beetle sex involves short breeding periods, intense competition and, of course, poo.

New evidence supports the theory that sexual activity lowers prostate cancer risk.

Changes in hormonal contraceptive use during a marriage could affect a woman's satisfaction, according to a new study that followed married couples for months to years.

Flaming sex involves make-up, elaborate group dances and seasonal monogamy.

New research shows how external genitals arose from very different starting places for reptiles and mammals.

Snake sex involves mating balls, battles similar to arm-wrestling and, sometimes, asexual reproduction.

Not unlike humans, male tree frogs call on females to begin the mating game, and females prefer long calls.

Though men who pledge to remain chaste until marriage get strong social support from Christian networks prior to marriage, they are left in the dark once they tie the knot.

Testosterone replacement therapies promise more muscle mass, more sex drive, more energy and maybe even that extra vigor in your golf swing, but at what cost?

A single gene that controls male and female sexes in one organism evolved from a simpler precursor gene in a unicellular algae, new research suggests.

For one night stands, size does matter, but it's not penis length that women are concerned about — it's girth, a new study suggests.

How does alcohol consumption affect romantic life? Let me count the ways.