Travel identification has taken many forms over the years, from stone tablets to an exhausting process that involved posting your itinerary on a church door. But how did we arrive at the standardized booklets many of us carry today? How do different countries use art and technology to distinguish their passports? And what’s the best (and worst) passport in the world, according to experts? Plus: Why you can blame a German spy for your embarrassing passport photo.

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Photo by Spencer Davis via Unsplash. Thanks, Spencer!

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Why does Germany use five different bins for recycling? Can you trick people into being greener by putting wolves on packaging? And is recycling a good business to be in? Plus, why Totes McGoats is one of the worst phrases of all time... but also perhaps the best recycling mascot ever. Featuring Christopher Hassiotis from HowStuffWorks.

This episode originally aired on January 24, 2018.

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Why did people start (and stop) dyeing pistachios red? How do thieves pull off high-stakes nut heists? What’s up with the coconut that looks like a butt? And why do so many members of the PTG team have beef with pine nuts? Today, we’re cracking the delicious mysteries of nuts (and, yes, things that aren’t technically nuts).

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Photo by Mae Mu via Unsplash. Thanks, Mae!

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Is our obsession with cleanliness keeping us from peak health? Also, can hookworm cure allergies? Will harvesting panda poop make you rich? Plus: Why Amish dust is superior to other dust (seriously!). Featuring Penny Sarchet.

This episode originally aired on June 14, 2017.

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Why is it so hard to stop oversleeping and eating candy? Why is it equally hard to start going to the gym and preparing healthy snacks? If you’ve been struggling with New Year’s resolutions, you’re not alone—turns out humans have wrestled with habits for centuries, like the guy who paid his servant to drag him out of bed in the morning. Will and Mango have the answers you need, with a little help from behavior change expert Dr. Katy Milkman.

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Remember, Monday, March 2 is the official 2026 Part-Time Genius Habit Change Fresh Start Day! Mark your calendars and let us know what habit you’re trying to change. Call our hotline at (302) 405-5925 or email higeniuses@gmail.com.

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We have ZERO intention of eating less food! But if you had to pare down your pantry to the bare minimum, what are the only foods you'd need to survive? Is an all-potato diet healthy? And did Steve Jobs' strange diet affect his business decisions? Plus, Will and Mango discuss the Woodstock for fruit lovers and find out why the elderberry might be the most overlooked berry. Featuring Spudfit.com's Andrew Taylor.

This episode originally aired on November 1, 2017.

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We honk at them in the street and shoo them away from our trash cans, but opossums are so much more than nocturnal nuisances. In today’s episode, Mango and Gabe get better acquainted with America’s only native marsupials, including the truth behind their famous talent for playing dead and their surprising connections to President Taft and Captain John Smith. Plus: A stirring ode to the opossum on Mango’s balcony and a tongue-in-cheek recipe for “planked possum.”

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Will and Mango are on a mission to uncover chocolate's darkest secrets. What's the difference between cacao and cocoa? Why have Swiss scientists been working on a pink chocolate for so long, and what does it really taste like? Plus, why does chocolate melt so perfectly in our mouths?

This episode originally aired on February 21, 2018.

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