Steve Brusatte knows every bird today is a living dinosaur, and as a paleontologist, he can tell you how that happened. Steve joins Hakeem to walk through the catastrophic asteroid impact 66 million years ago that ended the age of T. rex, and to explain why one small, beaked, seed-eating lineage was the only branch of the dinosaur family tree to survive. He traces the long and contested scientific history of the bird-dinosaur connection and the discovery by Chinese farmers in the 1990s that finally settled the debate. The age of dinosaurs did not end with the asteroid. It transformed.

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Guest Bio:

Steve Brusatte is a paleontologist at the University of Edinburgh, where he leads a research group studying dinosaur evolution and the history of life on Earth. He is the author of several acclaimed books, including The Rise and Fall of the Dinosaurs and The Story of Birds, and has served as a paleontology consultant on the Jurassic World film franchise. He will be featured in NOVA's upcoming five-part documentary series Evolution, coming fall 2026.

Steve Brusatte says T. rex wasn’t always the king, and as a paleontologist, he has spent his career uncovering how it got to the top of the food chain. Steve joins Hakeem to trace the full 100-million-year history of the tyrannosaur family, from its surprisingly small and nimble origins to the bone-crushing apex predator that ruled the end of the Cretaceous. They discuss how T. rex was not just a creature of brawn but also of remarkable intelligence, with keen senses of smell and hearing that made it the ultimate predator of its time. Along the way, they explore the diversity of tyrannosaur cousins including the long-snouted “Pinocchio rex” discovered on a Chinese construction site, and how shifting climates, mass extinctions, and continental drift shaped the dynasty's rise over millions of years.

Make sure to subscribe now so you never miss an episode. Learn more about NOVA and visit our YouTube channel.

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Guest Bio:

Steve Brusatte is a paleontologist at the University of Edinburgh, where he leads a research group studying dinosaur evolution and the history of life on Earth. He is the author of several acclaimed books, including The Rise and Fall of the Dinosaurs and The Story of Birds, and has served as a paleontology consultant on the Jurassic World film franchise. He will be featured in NOVA's upcoming five-part documentary series Evolution, coming fall 2026.

David Kaiser thinks the dark matter puzzle is getting closer to being solved.  Nearly a century of observations, from galaxy clusters to the cosmic microwave background, have built a compelling case for dark matter's existence, but in recent years, the leading candidates for this mysterious matter have been coming up short..  Enter black holes. Tiny ones. David explains how so-called primordial black holes that formed in the first moments after the Big Bang could possibly be all our dark matter… if they exist at all. Fortunately, this is a testable theory, and David explains the exciting new experiments that could potentially lay this cosmic mystery to rest. 

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Guest Bio:

David Kaiser is a professor of physics and the history of science at MIT. His research spans the history of modern physics, cosmology, and the foundations of quantum theory. He is the author of several books, including How the Hippies Saved Physics, and is a frequent contributor to public conversations about science and its history.

David Kaiser thinks a good place to hunt for tiny black holes might be… Mars? How do you detect something microscopic, invisible, and speeding through space? Primordial black holes have long eluded astrophysicists—if they exist at all. But the hunt is heating up. David joins Hakeem to explore how scientists are combing through old data and designing new experiments that could finally catch one of these elusive objects—and possibly not only solve the century-old mystery of dark matter, but also confirm the existence of Hawking Radiation. And, yes, he explains why Mars might hold the key. 

Make sure to subscribe now so you never miss an episode. Learn more about NOVA and visit our YouTube channel.

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Guest Bio:

David Kaiser is a professor of physics and the history of science at MIT. His research spans the history of modern physics, cosmology, and the foundations of quantum theory. He is the author of several books, including How the Hippies Saved Physics, and is a frequent contributor to public conversations about science and its history.

David Kaiser thinks tiny black holes from the dawn of time could be the solution to the dark matter puzzle. David joins Hakeem to discuss primordial black holes, tiny objects that may have formed in the first fraction of a second after the Big Bang. First proposed by Stephen Hawking more than 50 years ago, this hypothesis requires no new physics and no new particles, making it one of the most grounded ideas currently on the table… and one that may solve more than one cosmic mystery. David explains what these primordial black holes are, why many in the physics community are returning to this decades-old idea, and how it could potentially solve the dark matter mystery. 

Make sure to subscribe now so you never miss an episode. Learn more about NOVA and visit YouTube channel. 

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Guest Bio:

David Kaiser is a professor of physics and the history of science at MIT. His research spans the history of modern physics, cosmology, and the foundations of quantum theory. He is the author of several books, including How the Hippies Saved Physics, and is a frequent contributor to public conversations about science and its history.

David Kaiser knows the universe is hiding something enormous – and no one can see it. Dark matter appears to be all over our universe, but what is it? As a physicist and science historian, David joins Hakeem to discuss one of astrophysics most impossible puzzles. Nearly a century of observations -  from the motion of galaxy clusters to the rotation of individual galaxies to the subtle patterns in the cosmic microwave background -  has built a remarkably consistent case that most of the matter in the universe is invisible to us. Kaiser and Hakeem work through how that evidence accumulated, why the leading candidate explanations have become increasingly constrained, and one tantalizing idea that is getting physicists excited. 

Make sure to subscribe now so you never miss an episode. Learn more about NOVA and visit YouTube channel. 

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Guest Bio:

David Kaiser is a professor of physics and the history of science at MIT. His research spans the history of modern physics, cosmology, and the foundations of quantum theory. He is the author of several books, including How the Hippies Saved Physics, and is a frequent contributor to public conversations about science and its history.

David Kaiser knows the universe is hiding something enormous – and no one can see it. Dark matter appears to be all over our universe, but what is it? As a physicist and science historian, David joins Hakeem to discuss one of astrophysics most impossible puzzles. Nearly a century of observations -  from the motion of galaxy clusters to the rotation of individual galaxies to the subtle patterns in the cosmic microwave background -  has built a remarkably consistent case that most of the matter in the universe is invisible to us. Kaiser and Hakeem work through how that evidence accumulated, why the leading candidate explanations have become increasingly constrained, and one tantalizing idea that is getting physicists excited. 

Make sure to subscribe now so you never miss an episode. Learn more about NOVA and visit YouTube channel. 

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Guest Bio:

David Kaiser is a professor of physics and the history of science at MIT. His research spans the history of modern physics, cosmology, and the foundations of quantum theory. He is the author of several books, including How the Hippies Saved Physics, and is a frequent contributor to public conversations about science and its history.

Need to know how many leaves are on that tree? Paleobotanist Dr. Kirk Johnson shares the surprisingly nerdy method—because you never know when leaf math will come in handy.

For more, check out the extended interview with Kirk Johnson.

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Long before trees and grass, microbes were shaping our atmosphere. Evolutionary biologist Peter Girguis explains how ancient bacteria learned to split water for energy, and why their waste product changed Earth forever.

For more, check out the extended interview with Peter Girguis.

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How did animals first make the giant step from water to land? Evolutionary biologist Sean B. Carroll explains how the discovery of Tiktaalik—a fossil with both fish and limb-like features—revealed a key moment in evolution.

For more, check out the extended interview with Sean B. Carroll.

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