Clips from the NATURE episode "Holy Cow!" show the cow's digestive system and illustrate other naturally evolved and artificially selected traits of cattle.

This video-enhanced lesson focuses on how and why humans have been so successful in selectively breeding cattle to suit our needs, while also exploring the limitations and consequences of this success. (Grades 9-12)

Discover the habits of these giant carnivores and find out the polar bears' secrets for surviving in the Arctic.

THE NATURE OF SEX spans the globe to illustrate how an astonishing diversity of life forms find their mates and conceive, raise, and protect their offspring.

THE NATURE OF SEX spans the globe to illustrate how an astonishing diversity of life forms find their mates and conceive, raise, and protect their offspring.

THE NATURE OF SEX spans the globe to illustrate how an astonishing diversity of life forms find their mates and conceive, raise, and protect their offspring.

THE NATURE OF SEX spans the globe to illustrate how an astonishing diversity of life forms find their mates and conceive, raise, and protect their offspring.

THE NATURE OF SEX spans the globe to illustrate how an astonishing diversity of life forms find their mates and conceive, raise, and protect their offspring.