Kurzgesagt - In a Nutshell 2025: Episode Guide & Ratings

Humans assume aliens look human. But why would they? Let's explore what life might actually look like in strange, distant worlds.

Most of us love animals but also eat meat. Unfortunately, most animals we eat live in truly horrible conditions. We don’t torture them for better meat, just for cheaper meat. If we all paid just a bit more, we could avoid most animal suffering – often just for a few cents per meal. What would it truly cost us to avoid animal torture and still eat meat?

Reality is not real. Your world is a prediction. Every sight, sound, and touch you experience is the result of calculations your brain makes before reality even reaches you. It fills in gaps, fabricates details, and even alters time itself so you feel like you’re in control. But if everything you know is an illusion… what does that say about you? What does it mean for your choices? Is there even free will?

South Korea is heading toward a demographic collapse unlike anything the world has seen before. With the lowest fertility rate ever recorded and a rapidly aging population, the country faces a future of economic decline, shrinking cities, cultural erosion, and a vanishing workforce. By 2060, nearly half of South Koreans could be over the age of 65, and entire regions may be abandoned as the population continues to shrink. How did South Korea reach this point? Why might it no longer be possible to reverse the trend? And what does this mean for other countries on a similar path?

What happens when your time machine breaks and you end up stranded millions of years ago? You’ve landed in a world that’s nothing like today, facing deadly storms and unbearable heat, breathing toxic air. How can you survive long enough to make it back home?

Can jellyfish power Tokyo? What would happen if it rained bananas for a day? We're taking two of your most absurd (and brilliant) questions and answer them with real science.

Fentanyl is the deadliest illegal drug in US history by far. It’s often described as the ultimate high, but it’s actually an inferior, short-lived, and brutally addictive version of heroin. In this video, we explore what opioids do to your brain and body, what it feels like to take them, and why so many people are dying from Fentanyl overdoses without ever choosing to take it.

A war has been raging for decades in the jungles of Panama, as we fight one of the most terrifying parasites on Earth. It is so relentless that our best defense is to drop 100 million radiation-blasted, flesh-eating flies from the sky – every week. It’s one of the most successful biological campaigns in history, but it’s a war we can never stop fighting… and one we can’t afford to lose.

What happens when the immune system meant to protect you becomes your worst enemy? This is the betrayal of autoimmune diseases like Type 1 diabetes, multiple sclerosis, celiac disease, lupus, Crohn’s disease, and many others. What exactly goes on in your body and why does it happen in the first place?