Sarah Holt

It's death on an unimaginable scale, when a majority of Earth's species quickly die out. It's called "mass extinction," and it's happened at least five times before. Cataclysms, such as supervolcanoes or asteroids, are thought to cause these events, but some experts believe a manmade mass extinction could be next. Is our planet in trouble? And if so, is there anything we can do to stop the next catastrophic annihilation? Experts are traveling the world, performing groundbreaking scientific detective work to answer these very questions.

As the deadliest drug epidemic in US history rages, follow the cutting-edge work of doctors and scientists as they explore how ADDICTION affects the brain, and how we should address our opioid crisis.

Scientists are coming to understand fat as a dynamic organ—one whose size may have more to do with biological processes than personal choices. Explore the mysteries of fat and its role in hormone production, hunger, and even pregnancy.

Earth teems with a staggering variety of animals, including 9,000 kinds of birds, 28,000 types of fish, and more than 350,000 species of beetles. What explains this explosion of living creatures—1.4 million different species discovered so far, with perhaps another 50 million to go? The source of life's endless forms was a profound mystery until Charles Darwin brought forth his revolutionary idea of natural selection. But Darwin's radical insights raised as many questions as they answered. What actually drives evolution and turns one species into another? To what degree do different animals rely on the same genetic toolkit? And how did we evolve?

He went off to war an unknown soldier and returned a beloved national hero. Often dismissed as a "do-nothing" president and a good-natured bumbler, Dwight D. Eisenhower -- the last American president to be born in the 19th century -- was actually a skillful politician, a tough Cold War warrior, and one of America's most misunderstood and unappreciated presidents. Two-part documentary from American Experience.

MacArthur is a 1999 television documentary film about Douglas MacArthur, a United States General of the Army. Produced by PBS for The American Experience (now simply American Experience) documentary program, it recounts the significant events and controversies in MacArthur's life, from childhood to his death in 1964. Written and produced by Austin Hoyt, directed by Hoyt and Sarah Holt, and narrated by David Ogden Stiers.

Investigate how an asteroid vanquished the dinosaurs 66 million years ago. Join scientists as they drill into the impact crater and, for the first time, reconstruct the hell on earth that unfolded in the minutes, hours and months after the impact.

The rock pocket mouse is a living example of Darwin's process of natural selection. Evolution is happening right now everywhere around us, and adaptive changes can occur in a population with remarkable speed. This is essential if you're a mouse living in an environment where a volcanic eruption can reverse selective pressure in nearly an instant. The film features Dr. Michael Nachman, whose work on pocket mice reveals a complete story, from ecosystem to molecules, that demonstrates how random changes in the genome can take many paths to the same adaptation-a colored coat that hides them from predators.

The enigmatic nature of the Nixon presidency combined comparatively progressive legislative initiatives with a flagrant abuse of presidential power and the public trust. His achievements in expanding peaceful relations with China and the Soviet Union stand in stark contrast with his continuation of the war in Vietnam. Finally brought down by scandal and duplicity, his administration did much to erode the citizenry's faith in government.

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.

The art of origami reshapes the world, affecting drug development and future NASA space missions.

NOVA investigates the story of cannabis from the criminalization that has disproportionately harmed communities of color to the latest medical understanding of the plant. What risks does cannabis pose to the developing brain? How much do we know about its potential medical benefits? As cannabis becomes socially accepted, scientists are exploring its long-term health consequences.

What will it mean when most of us can afford to have the information in our DNA - all three billion chemical letters of it - read, stored, and available for analysis. Cracking Your Genetic Code reveals that we stand on the verge of such a revolution. Meet a cancer patient who appears to have cheated death and a cystic fibrosis sufferer breathing easily because scientists have been able to pinpoint and neutralize the genetic abnormalities underlying their conditions. But what are the moral dilemmas raised by this new technology? Will it help or hurt us to know the diseases that may lie in our future? What if such information falls into the hands of insurance companies, employers, or prospective mates? One thing is for certain: the new era of personalized, gene-based medicine is relevant to everyone, and soon you will be choosing whether to join the ranks of the DNA generation.

PBS' premier science series helps viewers of all ages explore the science behind the headlines. Along the way, NOVA demystifies science and technology, and highlights the people involved in scientific pursuits.

NOVA scienceNOW is a News magazine version of the long-running and venerable PBS science program Nova. Premiering on January 25, 2005, the series was originally hosted by Robert Krulwich, who described it as an experiment in coverage of "breaking science, science that's right out of the lab, science that sometimes bumps up against politics, art, culture". At the beginning of season two, Neil deGrasse Tyson replaced Krulwich as the show's host. Tyson announced he would leave the show and was replaced by David Pogue beginning season 6.