Richard Prum says there's a lot that traditional evolutionary biology can't explain. He thinks a neglected hypothesis from Charles Darwin — and insights from contemporary queer theory — hold the answer. Plus: You won't believe what female ducks use for contraception.

Thomas Hildebrandt is trying to bring the northern white rhinoceros back from the brink of extinction. The wildlife veterinarian tells Steve about the far-out techniques he employs, why we might see woolly mammoths in the future, and why he was frustrated the day the Berlin Wall came down.

She is one of the best basketball players ever. She’s won multiple championships, including five Olympic gold medals and four W.N.B.A. titles. She also helped negotiate a landmark contract for the league’s players. Sue Bird tells Steve Levitt the untold truth about clutch players, her thoughts about the pay gap between male and female athletes, and what it means to be part of the first gay couple in ESPN The Magazine’s Body Issue.

Conrad Wolfram wants to transform the way we teach math — by taking advantage of computers. The creator of Computer-Based Maths convinced the Estonian government to give his radical curriculum a try — so why is the rest of the world so resistant?

Ellen Langer is a psychologist at Harvard who studies the mind-body connection. She’s published some of the most remarkable scientific findings Steve has ever encountered. Can we really improve our physical health by changing our mind?

Author and YouTuber John Green thought his breakout bestseller wouldn’t be a commercial success, wrote 40,000 words for one sentence, and brought Steve to tears.

Suleika Jaouad was diagnosed with cancer at 22. She made her illness the subject of a New York Times column and a memoir, "Between Two Kingdoms". She and Steve talk about what it means to live with a potentially fatal illness, how to talk to people who've gone through a tragedy, and ways to encourage medical donations.

Caroline Paul is a thrill-seeker and writer who is on a quest to encourage women to get outside and embrace adventure as they age. She and Steve talk about fighting fires, walking on airplane wings, and finding awe in birdwatching.

Steve shows a different side of himself in very personal interviews with his two oldest daughters. Amanda talks about growing up with social anxiety and her decision not to go to college, while Lily speaks candidly about her battle with anorexia and the conversation she had with Steve that led her to seek treatment.

The economist Joseph Stiglitz has devoted his life to exposing the limits of markets. He tells Steve about winning an argument with fellow Nobel laureate Milton Friedman, why small governments don’t lead to more freedom, and why he’s not afraid to be an advocate.

Monica Bertagnolli went from a childhood on a cattle ranch to a career as a surgeon to a top post in the Biden administration. As director of the National Institutes of Health, she’s working to improve the way we find new treatments — despite regulatory constraints and tight budgets.

Nobel laureate, bestselling author, and groundbreaking psychologist Daniel Kahneman died in March. In 2021 he talked with Steve Levitt — his friend and former business partner — about his book "Noise: A Flaw in Human Judgment" (cowritten with Olivier Sibony and Cass Sunstein) and much more.

Google researcher Blaise Agüera y Arcas spends his work days developing artificial intelligence models and his free time conducting surveys for fun. He tells Steve how he designed an algorithm for the U.S. Navy at 14, how he discovered the truth about printing-press pioneer Johannes Gutenberg, and when A.I. first blew his mind.

After Haiti’s devastating earthquake, Rajiv Shah headed the largest humanitarian effort in U.S. history. As chief economist of the Gates Foundation he tried to immunize almost a billion children. He tells Steve why it’s important to take big gambles, follow the data, and own up to your mistakes.

"The Power of Habit" author Charles Duhigg wrote his new book in an attempt to learn how to communicate better. Steve shares how the book helped him understand his own conversational weaknesses.

Cat Bohannon’s new book puts female anatomy at the center of human evolution. She tells Steve why it takes us so long to give birth, what breast milk is really for, and why the human reproductive system is a flaming pile of garbage.

Economist Daron Acemoglu likes to tackle big questions. He tells Steve how colonialism still affects us today, who benefits from new technology, and why democracy wasn’t always a sure thing.

Journalist Walt Hickey uses data to understand how culture works. He and Steve talk about why China hasn’t produced any hit movies yet and how he got his own avatar in the Madden NFL video game.

Arnold Schwarzenegger has been a bodybuilder, an actor, a governor, and, now, an author. He tells Steve how he’s managed to succeed in so many fields — and what to do when people throw eggs at you.

Physicist Helen Czerski loves to explain how the world works. She talks with Steve about studying bubbles, setting off explosives, and how ocean waves have changed the course of history.

The filmmaker doesn’t want to be known only for his movies. He tells Steve why he considers himself a writer first, how it feels to be recognized for his role in "The Mandalorian," and why he once worked as a rodeo clown.

Economist Michael D. Smith says universities are scrambling to protect a status quo that deserves to die. He tells Steve why the current system is unsustainable, and what’s at stake if nothing changes.

Computer scientist Fei-Fei Li had a wild idea: download one billion images from the internet and teach a computer to recognize them. She ended up advancing the state of artificial intelligence — and she hopes that will turn out to be a good thing for humanity.

Data scientist Nate Silver gained attention for his election predictions. But even the best prognosticators get it wrong sometimes. He talks to Steve about making good decisions with data, why he’d rather write a newsletter than an academic paper, and how online poker led him to the world of politics.