Highlights: May 13-19

Musician John Legend and comedian Wanda Sykes discover the extraordinary stories of the free black ancestors they never knew about on “Finding Your Roots” at 7 pm Sunday.

Sherlock and Watson pursue the trail of the Baskerville experiments – top-secret government research on genetically engineered gigantic animals for military use on Masterpiece Mystery! Presents: “Sherlock, Series II” at 8 pm Sunday and 8 pm Saturday.

Johnny Carson: American Masters at 8 pm Monday explores the life and career of “The Tonight Show” host through unprecedented access to Carson’s personal and professional archives.

Clinton: American Experience part two of two at 7 pm Tuesday explores the story of an American president who rose from a broken childhood in Arkansas to become one of the most successful politicians in modern American history.

Nature at 7 pm Wednesday examines the day-to-day dramas of an extended family of koalas, seen through the eyes of the scientists studying their every move and vocalization on “Cracking The Koala Code”.

Nova at 8 pm Wednesday reveals the untold final chapter of the Spanish conquest of Peru: not the Spanish walkover familiar from popular accounts, but rather a protracted and complex war of astonishing brutality that almost led to the Spanish losing their precarious foothold in the Andes in “The Great Inca Rebellion.”

Follow famed paleoanthropologist Richard Leakey and his wife, Meave, daughter Louise and their colleagues as they work in the arid northern regions of Kenya’s Turkana Basin to unravel the mysteries of human evolution on Bones of Turkanaat 9 pm Wednesday.

The Decemberists and Gillian Welch showcase the best in contemporary songwriting on Austin City Limits at 10 pm Wednesday and 10 pm Friday.

Musician Chris Isaak talks about his career on Overheard with Evan Smith at 7 pm Thursday.

On Arts In Context at 7:30 pm Thursday, world-renowned classical guitarist Jorge Caballero performs the classic work Pictures At An Exhibition by Modest Mussorgsky.

Chet goes to Jefferson, Texas, on The Daytripper at 8:30 pm Thursday.

Independent Lens at 9 pm Thursday presents “Precious Knowledge”, a documentary providing an insider’s perspective as Arizona student leaders fight to save their ethnic studies classes.

Identify the busy bees in your garden and how to keep them around on Central Texas Gardener at noon Saturday. Tour the native gardens of Natural Bridge Caverns, where nature’s connection starts above ground.
Rising roots rock kings the Avett Brothers and Ohio-to-Austin transplants Heartless Bastards take over the Austin City Limits stage at 7 pm Saturday.