Love, Sex, and Cyanide—The Private Life of a Toxic Butterfly

Heliconian butterflies choose mates with similar wing patterns. Their genes make them do it.
Restoration of an American mastodon herd by Charles R. Knight

This Week in Sustainability: From Ice Age to Internet Age, Scientists Look for Clues to Species’ Extinctions

Scientists explore the causes--climate change, habitat destruction, and more--that decimated animals and humans alike, from Ice Age to Internet Age.
Giraffe

What Makes a Species?

Scientists have found there are actually four different species of giraffes. But what makes a species?