Researchers uncover the evolution of writing and the story of the alphabet, dating back to millennia-old carvings in an Egyptian turquoise mine.

New research on extremely primitive life forms called slime molds, which navigate through life without a brain, could reveal the fundamental rules underlying all decision making.

Scientists study the implications of CRISPR, how it may change the human race's relationship with nature and what it means for human evolution.

Consistently stunning documentaries transport viewers to far-flung locations ranging from the torrid African plains to the chilly splendors of icy Antarctica. The show's primary focus is on animals and ecosystems around the world. A comic book based on the show, meant to be used an as educational tool for kids, was briefly distributed to museums and schools at no cost in the mid-2000s.

"American Experience" combines dramatic re-enactments with commentary by historians and authors to present an absorbing look at the personalities, events and resources that have had a profound impact on the shaping of America's past and present. Many of the program's documentaries have received major honors in the broadcasting community, including Emmy, Peabodys and duPont-Columbia University awards.

This award-winning series presents compelling untold stories and covers a wide array of provocative subjects. "Explorer" aired for 25 years -- the longest-running documentary series in cable TV history -- before being relaunched in 2015 after a five-year hiatus. Each monthly episode of the new "Explorer" takes a similar deep dive inside a story from the pages of a recent National Geographic magazine issue, taking viewers not only to the most remote corners of the globe but also to the furthest reaches of the mind and deepest crevices of history -- on urgent missions of discovery.

"Frontline" offers an unflinching and compelling look at complex, vital and often-controversial subjects. Each broadcast consists of a long-form news documentary. Topics run the gamut -- from Bernie Madoff's intricate fraud and prisoner abuse at Abu Ghraib, to AIDs, racial issues and Wal-Mart's effect on the U.S. economy.

Since its premiere in 1986, this Emmy-winning documentary series has presented hundreds of hours comprising profiles of outstanding American cultural artists. Past subjects have included Charlie Chaplin, Helen Hayes, pop icon Andy Warhol, singer Billie Holliday and composer-conductor Leonard Bernstein.