Rather than mundane, lazy sex, sloths participate in quite the mating game. In fact, sloth sex involves high-pitched screams, promiscuity and eye-gouging battles.
Octopus mating involves shifting body colors, detachable "penises," long-distance mating and sexual cannibalism.
Fractures on spear points show, for the first time, that the first North Americans really did use spear-throwers to hunt from safe distances.
Snake sex involves mating balls, battles similar to arm-wrestling and, sometimes, asexual reproduction.
Long thought to show a random assortment of animals, an ancient two-handled wine cup may actually show one of the earliest depictions of Greek constellations.
Not unlike humans, male tree frogs call on females to begin the mating game, and females prefer long calls.
A young child who died 1,500 years ago is the earliest probable case of Down syndrome in the archaeological record, say scientists who examined the child's skeleton, particularly the skull.
Koalas may be cute and cuddly, sleeping 18 to 22 hours a day, but they can become vicious when it's time to get down to business. Here's a look at how the marsupials mate.