Season 47 - Episode Guide

In this two-hour special, renowned paleontologist Kirk Johnson takes us on an epic adventure through time at the polar extremes of our planet. Following a trail of strange fossils found in all the wrong places—beech trees in Antarctica, hippo-like mammals in the Arctic—Johnson uncovers the bizarre history of the poles, from miles-high ice sheets to warm polar forests teeming with life. What caused such dramatic changes at the ends of the Earth? And what can the past reveal about our planet's climate today—and in the future?

Dogs have long been dependable companions by our sides. But it wasn't always that way, and a look at their closest living relative, the wolf, makes it clear why. Research into dog domestication and intelligence offers clues into what the human-dog relationship is all about. And analyzing dogs' brain activity and genes may even help answer the question of whether dogs are in it for the food—or if they really love us.

Worshipped as a goddess, condemned as satanic, and spun into a stunning array of breeds, cats have long fascinated humans. But did we ever really domesticate them? And what can science tell us about our most mysterious companions?

From fruit flies to whales, virtually every animal sleeps. But why? Why do we need to spend nearly a third of our lives in such a defenseless state? Scientists are peering more deeply into the sleeping brain than ever before, discovering just how powerful sleep can be, playing a role in everything from memory retention and emotional regulation to removing waste from our brains. So why are we getting so little of it?

When the U.S. trade embargo left Cuba isolated from medical resources, Cuban scientists were forced to get creative. Now they've developed lung cancer vaccines that show so much promise, some Americans are defying the embargo and traveling to Cuba for treatment. In an unprecedented move, Cuban researchers are working with U.S. partners to make the medicines more widely available.

Do we control our fat, or does it control us? For generations, overweight individuals have been stigmatized and cast as lazy. But scientists are coming to understand fat as a fascinating and dynamic organ—one whose size has more to do with biological processes than personal choices. Through real-life stories of hunter-gatherers, sumo wrestlers, and supermodels, NOVA explores the complex functions of fat and the role it plays in controlling hunger, hormones, and even reproduction.

The coronavirus SARS-CoV-2 has upended life as we know it in a matter of mere months. But at the same time, an unprecedented global effort to understand and contain the virus—and find a treatment for the disease it causes—is underway. Join the doctors on the front lines of the fight against COVID-19 as they strategize to stop the spread, and meet the researchers racing to develop treatments and vaccines. Along the way, discover how this devastating disease emerged, what it does to the human body, and why it exploded into a pandemic.

Eagles dominate the skies. But what makes these predators so special? Researchers study one special bird—and stunning up-close footage reveals her exceptional strength, eyesight, and flying skills. With intimate access to a new bald eagle family, NOVA takes you into the nest to witness the drama of chicks struggling to survive. 

Human Nature: Our DNA can determine attributes from eye color to medical predispositions. With an extraordinary new technology called CRISPR, we can now edit DNA—including human DNA. But how far should we go? Gene editing promises to eliminate certain genetic disorders like sickle cell disease. But the applications quickly raise ethical questions. Is it wrong to engineer soldiers to feel no pain or to resurrect an extinct species? And is there harm in allowing parents to choose their child's features, like eye color or height? The scientists who pioneered human genome studies and CRISPR grapple with these questions. 

CRISPR Gene-Editing Reality Check: The revolutionary gene-editing tool known as CRISPR can alter, add, and remove genes from the human genome. The implications are immense: It could help eliminate illnesses like sickle cell disease and muscular dystrophy and could even allow us to alter the genes of future generations of humans, leading to so-called designer babies. But will this ever really happen? Medical journalist and pediatrician Alok Patel investigates the current state of CRISPR—starting with a bull calf named Cosmo. Patel discovers how scientists edited Cosmo's genome so he would produce more male offspring and what that means for humans. In conversation with scientists, artists, and ethicists, Patel explores what kind of gene editing is actually possible right now—and what we should be thinking about when we consider manipulating human traits and, ultimately, the human experience. 

Who says you need brains to be smart? Extremely primitive life-forms called slime molds can navigate mazes, choose between foods, and create efficient networks—no brain required. New research on these organisms, which are neither plant nor animal, could help reveal the fundamental rules underlying all decision making.

Where would we be without the world's alphabets? Writing has played a vital role in the expansion and domination of cultures throughout history. But researchers are only now uncovering the origin story to our own alphabet, which may have gotten its beginnings in a turquoise mine 4,000 years ago. From the shape of the letter A to the role of writing in trade and storytelling, discover how the written word shaped civilization itself.

Just as writing changed the course of human history, the evolution of paper and printing revolutionized the spread of information. The printing press kicked off the Industrial Revolution that fast-tracked us to the current digital age. But as the 4,000-year-old tradition of penmanship falls out of favor, should we consider what might be lost in this pursuit of ever more efficient communication?

For animals in Mozambique's Gorongosa National Park, the normal balance of competition and predation was upended when a war wiped out the top predators. The remaining animals didn't simply grow in numbers—they began behaving in unusual ways, veering outside their typical territories and feeding patterns. Could it be that it's not just predators' kills that keep other populations in check, but also the fear they inspire? NOVA joins a team of scientists as they reintroduce wild dogs to Gorongosa to find out if restoring the park's "landscape of fear" can restore balance to an entire ecosystem.

In October 2020, a NASA spacecraft called OSIRIS-REx attempts to reach out and grab a piece of an asteroid named Bennu to bring it back to Earth. The OSIRIS-REx team has just three chances to extend its spacecraft's specialized arm, touch down for five seconds, and collect material from the surface of Bennu. But if they can pull it off, scientists could gain great insight into Earth's own origins—and even learn to defend against rogue asteroids that may one day threaten our planet. 

As global temperatures continue to rise, scientists are wondering if we need solutions beyond reducing emissions. Enter geoengineering. From sucking carbon straight out of the air to physically blocking out sunlight, the options may seem far-fetched. But as time runs out on conventional solutions to climate change, scientists are asking the hard questions: Can geoengineering really work? How much would it cost? And what are the risks of engineering Earth's climate?

When the roof of Notre Dame Cathedral erupted in flames in April of 2019, firefighters battled for nine grueling hours to save the historic landmark. Still, Paris came alarmingly close to losing more than 800 years of history. Now engineers are in a different race against time: to rebuild the roof and secure the medieval structure of Notre Dame. Underneath the charred scaffolding and vaulted ceilings of the cathedral, scientists study the components of Notre Dame's iconic design to puzzle out how best to repair it.

Diabetes and pre-diabetes affect over 100 million people in the U.S., costing more than $325 billion each year. It's now predicted that one in three children born since 2000 will develop the disease. "Blood Sugar Rising" puts human faces to these statistics, exploring the history and science of the illness through portraits and voices of Americans whose stories shape the film. Together, they present a dramatic depiction of this hidden national crisis. The two-hour special also reveals new hopes—from the rise of safer and easier medical treatments to new discoveries about lifestyle and environmental factors, the documentary follows those taking action to improve diabetes management and prevention.