Long recognized as one of the most intelligent birds, the raven also has a less than savory image throughout history as a scavenger that does not discriminate between humans and animals. Ingenious and versatile, ravens are members of the crow family, which includes jays and magpies. They are found everywhere in the northern hemisphere and ...

The first video is a preview of NATURE's two-part special DOGS THAT CHANGED THE WORLD, and tells the epic story of the wolf's evolution, how ''man's best friend'' changed human society and we in turn have radically transformed dogs. Part one, ''The Rise of the Dog,'' premiered Sunday, April 22 on PBS. Part two, ''Dogs by Design,'' ...