Species of monkey previously unknown to scientists discovered in the Congo, 390 million-year-old mollusk reconstructed in 3-D, and spongy tissue found in human hearts also found in those of reptiles.

Researchers from the University of Helsinki may be on the trail to the answer to an age-old question: why do dogs chase their tails?

Cloned horses may compete in future Olympic games, the valuable role wasps play in wine production, and a new study shows that monkeys notice when others make mistakes.

(Airs Sunday, May 23) Are you cat-crazy or a dog die-hard? Watch as NATURE shares the stories of pet owners and their beloved animals.

Cats command our attention and our devotion. These fascinating creatures have been perplexing people for thousands of years.