Even though they are the smallest of all the monkeys, pygmy marmosets can leap more than 16 feet. They expertly maneuver through the canopy.

Accompany researchers in "Deep Jungle: The Beast Within" as they explore tropical forests for clues about the origins of humans and what our own future might hold.

View additional resources for NATURE's "Deep Jungle: Monsters of the Forest."

They are the world's macaws -- long tailed parrots that are both greatly beloved -- and terribly endangered. And, for the most part, poorly understood.

Bernard Walton, a BBC producer, spent many months trekking through Gabon while making Mask of the Mandrill.