Nova: “How Writing Changed the World”

“Nova” explores new discoveries and how we have come this far. Except where otherwise noted, all times below are Wednesdays at 8 p.m. on Arizona PBS.

September 9 at 7 p.m.: “Human Nature”

Our DNA can determine attributes from eye color to medical predispositions. An extraordinary technology called CRISPR allows us to edit human DNA, possibly eliminating genetic diseases or choosing our children’s features. But how far should we go? Watch online.

September 16: “Secret Mind of Slime”

Scientists investigate the bizarre “intelligence” of slime molds, which appear to learn and make decisions – without a brain. These cunning, single-celled blobs can navigate mazes and create efficient networks. Can they also redefine cognition? Watch online. 

September 23: “How Writing Changed the World, Hour 1”

Writing shaped civilization itself, from the trading of goods to tales of ancient goddesses and kings. Follow the evolution of the written word, from millennia-old carvings in an Egyptian turquoise mine to our modern-day alphabets. Watch online.

September 30: “How Writing Changed the World, Hour 2”

Just as handwritten records changed how societies work, the printing press transformed the spread of information, igniting the Industrial Revolution. How did technologies – from pento paper to printing press – make it all possible?

October 7 at 9 p.m.: “Animal Espionage”

Camera traps and drones are revolutionizing the study of wildlife by providing an up-close look at cameras without disturbing them. See how these technologies are helping us understand everything from mysterious whale behavior to tiger migration.

October 14: “Nature’s Fear Factor”

When top predators disappeared from Mozambique’s Gorongosa National Park, other animals fell into unusual patterns. Now scientists are reintroducing wild dogs to restore the park’s “landscape of fear” and with it the natural balance of the ecosystem.

October 21: “Touching The Asteroid”

If spacecraft OSIRIS-REx can grab a piece of an asteroid and bring it back to Earth, scientists could gain great insight into our planet’s origins, and even how to defend against rogue asteroids. But NASA only gets three shots at collecting a sample.

October 28: “Can We Cool The Planet?”

As global temperatures rise, scientists are exploring geoengineering solutions, from planting trees to sucking carbon out of the air to physically blocking out sunlight. But would it work? And what are the risks of engineering Earth’s climate?

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'Last Tango in Hailfax' returns for season four

After seven years of marriage, Alan and Celia discover that wedded bliss isn't always blissful. Clashing politics, Alan's new job and a wild local lad create tension. Caroline gets emotionally embroiled at work. Alan's brother visits. See what else unfolds in season four of "Last Tango in Hailfax."

'Nature' explores the wild on Wednesday nights

From the remarkable octopus to a river of dreams, experience compelling stories of the natural world as "Nature" returns to Arizona PBS Wednesday nights at 7 p.m.

Family Night: PBS KIDS movie marathon

Arthur and his friends gather on the couch with popcorn.

This weekend Arizona PBS KIDS is delivering a mini-marathon of hour-long specials! On Sept. 25, 26 and 27, join us at for "WordGirl: The Rise of Miss Power" at 6 p.m., "Odd Squad: World Turned Odd" at 7 p.m., "Rhythm and Roots of Arthur" at 8 p.m., and "Wild Kratts: Amazon’ Amazon Adventure" at 9 p.m.