In part 1 of our special series on human ancestry, we tour through our family tree to meet our ancestors and distant cousins, and to find out what made us human along the way. The story of human ancestry is not a simple progression from...

If being alive on Earth were a contest, humans would win it hands down. We're like the Michael Phelps of being alive, but with 250,000 times more gold medals. Today Hank is here to tell us the specifics of why and how human population...

Around 74,000 years ago, a volcano called Toba in Sumatra exploded, and some scientists think it had a serious impact on the human population and some...don't.

Why do humans cook? Holidays are celebrated in many ways, but chances are they involve eating, and eating a LOT. Ever wonder why we cook our food? We do it because it tastes good, of course, and because our customs and traditions are...

We’ve told you before that there really isn’t any evidence that animals consume mind-altering substances because they feel good to them. This makes it appear that the fondness for psychoactive drugs is, pretty...human. What is it about...

You've probably seen the pyramidal diagram of Maslow’s hierarchy of needs. It's straightforward enough but, it might be a bit too subjective to really measure human needs.

Scientists often use the phrase “anatomically modern humans” to describe the point when our ancient ancestors looked like us. But when did humans become behaviorally modern?

"Co-parenting" isn't a buzzword -- it's a way of showing up for your family openly, consistently and lovingly, says storyteller and father Joel Leon. In this moving talk, he challenges all parents to play an equal, active role in their...

With a solid understanding of biology on the small scale under our belts, it's time for the long view - for the next twelve weeks, we'll be learning how the living things that we've studied interact with and influence each other and...

Hank and his brother John discuss heredity via the gross example of relative ear wax moistness.

Paul Andersen explains how DNA replication ensures that each cell formed during the cell cycle has an exact copy of the DNA. He describes the Meselson-Stahl experiment and how it showed that DNA copies itself through a semi-conservative...

Malaria is a global disease that we've beaten back around the world, including in some tropical places, but we’ve had the hardest time in...

Animals eat their own poop in order to gain extra access to nutrients or to microbes that help digest those nutrients.



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Why do Bats Transmit So Many Diseases Like Ebola

Ever not felt completely like yourself? There's a good reason for that. Because a large part of you isn't actually you. Our bodies are home to ten times as many microbes as human cells. We are walking ecosystems, each of us home to...

Before we dive into the big questions of philosophy, you need to know how to argue properly. We’ll start with an overview of philosophical reasoning and breakdown of how deductive arguments work (and sometimes don’t work).

In 2013, a treasure trove of unusual fossils were uncovered in a cave in South Africa, and researchers soon realized: these were the remains of a new species of ancient humans. Paleoanthropologist Juliet Brophy takes us inside the...

Green-minded architect and designer William McDonough asks what our buildings and products would look like if designers took into account "all children, all species, for all time."

While you unwrap that luscious truffle, let Hank explain the science of chocolate -- where it comes from, what its active ingredient is, and how it works. Also learn the difference between chocolate, cocoa, cacao and coca, so you really...

With stunning photos and stories, National Geographic Explorer Wade Davis celebrates the extraordinary diversity of the world's indigenous cultures, which are disappearing from the planet at an alarming rate.

Welcome to Crash Course Theater with Mike Rugnetta! In this, our inaugural week, we're going to ask the two classic questions about theater. 1.What is theater? And 2. Is it spelled -re or -er? Well, there's a clue to question two in the...

What does Psychology mean? Where does it come from? Hank gives you a 10 minute intro to one of the more tricky sciences and talks about some of the big names in the development of the field. Welcome to Crash Course Psychology!!!

In which John Green explores how Spain went from being a middling European power to one of the most powerful empires on Earth, thanks to their plunder of the New World in the 16th and 17th centuries. Learn how Spain managed to destroy...

In which John Green explores how Spain went from being a middling European power to one of the most powerful empires on Earth, thanks to their plunder of the New World in the 16th and 17th centuries. Learn how Spain managed to destroy...