Particles of Thought

Fossilization isn’t luck - it’s geology. Paleobotanist Kirk Johnson explains how fossils only form in certain conditions, the tricks to finding them, and why one fossil leaf can lead to thousands more. For more, check out the extended interview with Kirk Johnson.Learn more about NOVA and subscribe to our YouTube channel. 

Speech is rare in the animal kingdom because it requires a very specific brain architecture. Neuroscientist Erich Jarvis explains how duplicating neural pathways for movement unlocked language, dancing, and even advanced problem-solving in more than just humans.For more, check out the extended interview with Erich Jarvis. Learn more about NOVA and subscribe to our YouTube channel. 

How does evolution invent entirely new things, like limbs, wings, and venom? Evolutionary biologist Sean B. Carroll joins us to reveal the hidden rules behind nature’s creativity and the genetic toolkit that makes it possible. Carroll explains how the same set of genes can build wildly different creatures — from fruit flies to lobsters — simply by rewiring their genetic circuits. Discover why developmental biology holds the key to understanding evolution, how snake venom evolved, and why medicines like GLP-1 drugs and statins trace their origins to nature’s own innovations. Plus, what the emergence of new species tells us about life’s future and the surprising power of evolution to repurpose old parts in new ways. Learn more about NOVA and subscribe to our YouTube channel. —————————Guest Bio: Sean B. Carroll is a renowned evolutionary biologist and author whose work has inspired a deeper public understanding of evolution and the natural world. He is an Investigator at Howard Hughes Medical Institute (HHMI), where he was formerly Head of HHMI Tangled Bank Studios, and led the Department of Science Education from 2010-2023. He is also a Professor of Biology at the University of Maryland. His research focuses on genes that influence the evolution of animal diversity.Timestamps(00:00:00) How Does A New Species Evolve?(00:12:54) The Process of Speciation: Use It or Lose It(00:36:22) Development: What the Fruit Fly Taught Us(00:55:37) The Evolution of Defense Mechanisms & Developing Medications(01:19:55) The Role of Chance in Evolution(01:24:22) Credits

From legs on heads to missing eyes, fruit fly mutations exposed the genetic toolkit that builds all animals. Evolutionary Biologist Sean B. Carroll shows how these discoveries rewrote our understanding of evolution.For more, check out the extended interview with Sean B. Carroll.Learn more about NOVA and subscribe to our YouTube channel. 

From snakes to jellyfish, venom is one of evolution’s most lethal inventions. Evolutionary Biologist Sean B. Carroll reveals how this deadly innovation emerged—and the new science behind antivenom inspired by nature’s own defenses.For more, check out the extended interview with Sean B. Carroll.Learn more about NOVA and subscribe to our YouTube channel. 

The edge of a black hole isn’t what you think. Astrophysicist Janna Levin dives into the event horizon, the one-way transition where space and time warp so much that escape becomes as impossible as reversing the clock.For more, check out the extended interview with Janna Levin.Learn more about NOVA and subscribe to our YouTube channel. 

There’s no single ‘smoking gun’ for life beyond Earth. Microbiologist Peter Girguis explains the subtle fingerprints scientists hunt for—and why finding them on Mars could change everything.For more, check out the extended interview with Peter Girguis.Learn more about NOVA and subscribe to our YouTube channel. 

Scientists are editing genes for human speech into mice to see if they can learn vocal patterns. Neuroscientist Erich Jarvis explains how this could unlock not just speech—but entirely new ways of thinking.For more, check out the extended interview with Erich Jarvis. Learn more about NOVA and subscribe to our YouTube channel. 

Can we bring extinct species back to life? Evolutionary biologist Beth Shapiro claims we just did. As Chief Science Officer at Colossal, her team made headlines in spring 2025 with the announcement of the de-extinction of the dire wolf. She takes us behind the headlines to explain how this is no “Jurassic Park” fantasy. She breaks down exactly how her team used ancient DNA, CRISPR genome editing, and the genomes of modern relatives to bring back lost traits and create animals capable of thriving in today’s ecosystems. Along the way, she dives into the surprising challenges of this work — from the quest for artificial wombs to the ethics of genetic engineering — and reveals how the same tools powering de-extinction are already helping endangered species survive. Learn more about NOVA and subscribe to our YouTube channel. —————————Guest Bio: Beth Shapiro is an evolutionary biologist and Chief Science Officer at Colossal, a company notably responsible for the de-extinction of  the dire wolf. She is also a professor of Ecology and Evolutionary Biology at UC Santa Cruz. Her research focuses on species evolution and the continued impact of human activities, considering questions about domestication, speciation and pathogen evolution. She is also exploring techniques to recover trace amounts of DNA from samples and the possible role of genomic technologies in the fields of conservation and medicine.Timestamps(00:00) What is De-Extinction? Reviving the Dire Wolf(29:45) Ethics and Backlash for Cloning (38:10) Modifying DNA to Bring Species Back to Life(45:31) The Future of De-Extinction(54:30) Credits

Jurassic Park got it all wrong. Beth Shapiro would know… she’s Chief Science Officer at Colossal, the genetic engineering company that recently made headlines for bringing back the extinct dire wolf. She breaks down how de-extinction is really done, and why Jurassic Park can never happen.For more, check out the extended interview with Beth Shapiro.Learn more about NOVA and subscribe to our YouTube channel. 

The deepfake game is getting real. Deepfake detective Hany Farid gets under the hood of AI and explains exactly how it can now make such convincing fake content –  so convincing that he himself has trouble identifying his own real voice from an AI-generated fraud. Can you spot the deepfake?For more, check out the extended interview with Hany Farid.Learn more about NOVA and subscribe to our YouTube channel. 

Ever wonder why you get déjà vu? Or why you keep losing your keys? Your brain does some weird stuff. Neuroscientist Heather Berlin explains the surprising science behind these everyday mysteries.For more, check out the extended interview with Heather Berlin.Learn more about NOVA and subscribe to our YouTube channel. 

Space itself rings with gravitational waves when black holes collide—the most powerful events detected since the Big Bang. Astrophysicist Janna Levin reveals why, when the cosmic symphony fades, the merged black hole is stripped to flawless simplicity.For more, check out the extended interview with Janna Levin.Learn more about NOVA and subscribe to our YouTube channel. 

Could a Martian rock hold the most promising sign of life beyond Earth? Microbiologist Peter Girguis unpacks NASA’s stunning discovery of ‘leopard spots’ on a rock from Mars’s Jezero Crater—and why they look eerily like the handiwork of microbes on our own planet.For more, check out the extended interview with Peter Girguis.Learn more about NOVA and subscribe to our YouTube channel. 

A sinkhole can become a time capsule full of skeletons - layers upon layers of beasts that once walked the Earth - and Florida’s landscape is full of them. Discover the surprising science of how Florida’s sinkholes form, what they really are, and what can be found inside them. Come along with Dr. Kirk Johnson, Sant Director of the Smithsonian Institution National Museum of Natural History, as he describes what he calls "the best sinkhole experienceFor more, check out the extended interview with Kirk Johnson.Learn more about NOVA and subscribe to our YouTube channel. 

In a world flooded with fake videos and voice recordings that seem real, how can you detect deepfakes? Turns out, there are some aspects of the physical world that are not yet known to artificial intelligence - and those gaps are the key. Expert Hany Farid reveals techniques that can be used to detect AI-generated media.For more, check out the extended interview with Hany Farid. Learn more about NOVA and subscribe to our YouTube channel. 

What do deep-sea microbes and Martian “leopard spots” have in common? Marine biologist Peter Girguis thinks they might both hold clues to finding life beyond Earth. In this episode, he joins Hakeem for a journey from the ocean floor to outer space, sharing stories from his dives aboard the Alvin submersible and exploring how Earth’s most extreme lifeforms could help us find the first ETs. Along the way, he explains how Earth is truly a microbial planet — teeming with enough microbes to stretch across the galaxy –  reshaping how we think about life, both here and out there. Learn more about NOVA and subscribe to our YouTube channel. —————————Guest Bio: Peter Girguis is a professor of Organismic and Evolutionary Biology at Harvard University. His research focuses on marine organisms, and how they adapt to extreme environments. He also works on developing novel technologies like deep sea autonomous laboratories and microbial fuel cells. Girguis appears in NOVA’s Ancient Earth seriesTimestamps(00:00:00) Microbes Rule the Planet(00:13:45) Deep Ocean Exploration(00:36:30) Signs of Life on Mars(00:54:18) Other Life in Outer Space(01:01:23) Two Truths and a Lie: Science Headlines(01:07:00) The Future of Working With Microbes(01:11:22) Credits

Talking, singing, even dancing — they all trace back to a rare superpower: vocal learning. But humans aren’t the only animals that have it. Neuroscientist Erich Jarvis has spent his career decoding the mysterious ability to imitate sounds, a key ingredient in spoken language. In this episode, he joins Hakeem to explore why only a handful of species — like parrots, dolphins, and bats — can do it, how it evolved, and what it reveals about the brain, consciousness, and culture. Plus, Erich shares how AI is helping decode animal communication  and why engineering our pets to talk might actually be possible… but could fundamentally change the way they think. Learn more about NOVA and subscribe to our YouTube channel. —————————Guest Bio:Erich Jarvis is a neuroscientist investigating the mysteries of speech and vocal learning through groundbreaking research on birdsong and brain evolution. As a professor at The Rockefeller University and head of the Jarvis Lab, he explores how complex behaviors like human language arise from brain circuits and genetic pathways. Jarvis was also profiled in NOVA Wonders: What are Animals Saying.Timestamps(00:00:00) Language in Animals vs. Humans(00:10:37) Music and Vocal Learning(00:20:15) Can You Genetically Engineer Animals to Speak?(00:27:48) How Did Speech Evolve?(00:36:09) Can We Translate Animal Language? (00:42:27) Brain Size and Speech(00:48:14) Writing & Symbolic Communication (00:57:00) Conclusion(01:04:02) Credits

Your brain does all kinds of strange things — and neuroscientist Heather Berlin wants to explain how it works. In this episode, she joins Hakeem to explore the mysteries of the mind: how consciousness works, how your brain constructs reality, and how you might be able to hack it to live a better life. They dive into the effects of psychedelics and meditation, and explore the future of thought in a world shaped by AI. This episode is no placebo – it really will expand your mind. Learn more about NOVA and subscribe to our YouTube channel. --------------------------Guest Bio:Heather Berlin is a neuroscientist, clinical psychologist, and associate clinical professor of psychiatry and neuroscience at the Icahn School of Medicine at Mount Sinai in New York. She is interested in how consciousness and creativity work within the brain and is also the host of NOVA’s "Your Brain" two-part special.Timestamps(00:00:00) What is Consciousness?(00:09:38) Perception Box(00:22:18) What's My Brain Doing? Deja Vu, Goosebumps & More(00:34:45) Cognitive Behavioral Therapy & Ketamine Treatment(00:44:55) Thoughts and Creative Flow States(00:58:02) Aversive Conditioning: Addiction, Anxiety, and Behavior(01:08:06) Fame & Fulfillment(01:18:02) The Future of Neuroscience(01:29:09) Credits

The universe loves making things complicated. From minerals and microbes to languages and societies, complexity keeps showing up — but why? Astrobiologist Mike Wong and mineralogist Bob Hazen think we’re missing a law of nature to explain this phenomenon. Hakeem sits down with them to understand – and kick the tires on – their bold new idea: what they call a Law of Increasing Functional Information. They break down how it works, why it matters, and how it could reshape our understanding of everything from life to language to the universe itself.Learn more about NOVA and subscribe to our YouTube channel. --------------------------Guest Bios:Robert Hazen is a mineralogist and astrobiologist at Carnegie Science and George Mason University. His pioneering research explores the origins of life and the evolving diversity of minerals on Earth. A prolific author and public communicator, Hazen has written widely on science, complexity, and the deep connections between the physical and biological worlds.Mike Wong is an astrobiologist and planetary scientist at Carnegie Science whose work focuses on how life begins and evolves on worlds like our own. He is also a science communicator, hosting the podcast Strange New Worlds, where he brings complex cosmic ideas to broad audiences. Wong’s research and outreach bridge cutting-edge science with big-picture questions about life in the universe.Their new book Time's Second Arrow: Evolution, Order, and a New Law of Nature will be available in February 2026.Timestamps(00:00:00) Introduction(00:05:28) Laying Out the "Law of Increasing Functional Information"(00:22:50) Functional Information: Explained(00:30:17) What is Selection? Discussing the Law(00:51:34) Testing the New Law(01:11:24) Credits