Why do animals do what they do? It’s a huge question, and in this episode, we’ll learn how scientists break it down. We’ll talk about the proximate and ultimate studies they use to understand animal behavior, and some of what they’ve learned along the way — including how much decision-making other animals are really doing.
Chapters:
Introduction: Animal Behavior
Proximate Level
Ultimate Level
Innate Behaviors
Complex Behaviors
Review & Credits
Credits

The world is full of microbes and viruses that can get us sick, but we’ve got an Avengers-style defense system ready to take them on. In this episode of Crash Course Biology, we’ll learn about an animal’s immune system, from their skin to inflammatory responses, to the adaptive immune system and all the special cells and antibodies that come with it.
Chapters:
Introduction: Defending Against Pathogens
The Integumentary System
Internal Defenses
Asymptomatic Infections
Healing
Adaptive Immunity & Vaccines
The Lymphatic System
Review & Credits
Credits

Hank discusses the process by which organisms grow and develop, maintaining that, in the end, we're all just tubes.

Chapters:
1) Zygote
2) Morula
3) Blastula
4) Radial Symmetry
5) Bilateral Symmetry
6) Gastrulation
7) Blastopore
8) Gastrula
9) Protostomes & Deuterostomes
10) Germ Layers
a) Diploblastic
b) Triploblastic
11) Biolography

When you think about the body’s infrastructure, you probably think of bones. But what about the heart, the blood vessels, and the lymphatic system? In this episode of Crash Course Biology, we’ll tour the cardiovascular, lymphatic, and musculoskeletal systems, learning how all of them keep a vertebrate’s inner workings connected, powered up, and ready to move.
Chapters:
Introduction: The Body's Infrastructure
Blood Vessels & Capillaries
The Heart
Vivien Thomas
The Lymphatic System
The Musculoskeletal System
Review & Credits
Credits

Social behavior like caring for our young, fighting off rivals, joining a pack, or even fusing together into a huge super animal like the Power Rangers, adds a whole other layer of complexity to the lives of animals out there. And it even raises questions about being, culture, and what it means to be an individual. So today, we're going to dive into the amazing ways animals interact with other animals, live a day in the life of the Portuguese Man O'War, and learn how these complex social interactions can go way beyond anything humans are capable of!

Today we are introducing a new area of philosophy – philosophy of religion. We are starting this unit off with Anselm’s argument for God’s existence, while also considering objections to that argument.

In which John Green, Hank Green, and Emily Graslie teach you about the Anthropocene, an unofficial geological era that covers the last century or so, in which humanity has made massive progress. We've discovered the Higgs-Boson particle, and awesome electric cars, and amazing smartphones. So all this collective learning and progress has been good for everyone, right? Maybe not. We'll look at some of the pros and cons of all this "progress," including environmental impact, changes in the way people live and work, and political changes and wars that come along with the modern world. We've come a long way, but there's a long way to go. Crash Course will also take a look at what's going to happen in the near future. If we manage to make our way through the coming bottlenecks, we could be OK in coming centuries. Don't get too hopeful, though. The Sun will eventually die, and the Earth will be destroyed, and later the universe will eventually experience heat death. But we won't talk about those downers until next week.

Today we explore what obligations we hold with our personal beliefs. Hank explains epistemic responsibility and the issues it raises with everything from religious belief, to ship owning, to vaccinations.

I don't mean it mean, but today we're going to be cruel. It's the fun-loving Theater of Cruelty, which was pioneered by the genius Antonin Artaud in France during the inter-war period in twentieth century. The Theater of Cruelty was meant to force an audience into looking at the ridiculous illusions of their bourgeois lives. Is it entertaining? Not always. Was it hugely influential? Absolutely.

Francis Ford Coppola's "Apocalypse Now" is a different kind of war movie. It's a multi-genre film that maybe says more about human psychology than it does about war. In this episode of Crash Course Film Criticism, Michael Aranda takes us on a trip through the Vietnam War through the eyes of a director at the end of his rope.

Mike Rugnetta is going to tell you stories of death, destruction, divine judgment, damnation, and the occasional happy ending. That's right, this week we're talking about the Apocalypse. Actually, we're talking about a bunch of ways the world could end. Prepare for stories of the end times from Judaism, Zoroastrianism, Christianity, and Islam! It's the (mostly) Abrahamic Apocalypses on Crash Course World Mythology.

Our unit on the philosophy of religion and the existence of god continues with Thomas Aquinas. Today, we consider his first four arguments: the cosmological arguments.

In which John Green teaches you about the war that was supposed to end all wars. Instead, it solved nothing and set the stage for the world to be back at war just a couple of decades later. As an added bonus, World War I changed the way people look at the world, and normalized cynicism and irony. John will teach you how the assassination of an Austrian Archduke kicked off a new kind of war that involved more nations and more people than any war that came before. New technology like machine guns, airplanes, tanks, and poison gas made killing more efficient than ever. Trench warfare and modern weapons led to battles in which tens of thousands of soldiers were killed in a day, with no ground gained for either side. World War I washed away the last vestiges of 19th-century Romanticism and paved the way for the 20th-century modernism that we all know and find to be cold and off-putting. While there may not be much upside to WWI, at least it inspired George M. Cohan to write the awesome song, "Over There."

Chapters:
Introduction: The Great War
Causes of World War I
Who is to blame for starting WWI?
Trench Warfare
Combatants From Around the World
Casualties of World War I
Soldiers' Sentiments During the WWI
An Open Letter to Alcohol
Outcomes of WWI
Credits

This week on Crash Course Mythology, Mike is teaching you about the archetypes that are often associated with male divinities. We’re going to talk about Fathers & Sons, Kings & Judges, Saviors & Sages, Shamans, Tricksters, and Lords of Destruction. Along the way, we’ll look at the story of Hwaning, Hwanung, and Dangun from the Korean peninsula, and we’ll learn about Arjuna and all the help he got from Krishna. We’ll also touch on a ton of other myths from around the world. These things play out this way all the time, man.

Climate change has no bias, but our societies and systems do. And although it’s a danger to all of us, a changing climate affects some groups disproportionately, raising issues of justice and equity. In this episode of Crash Course Climate and Energy, we’ll take a look at the ways injustice within societal structures causes climate change to affect some more than others and discuss some of the work that environmental justice advocates are doing in response.

Chapters:
Introduction: The Rohingya & Climate Inequality
How Climate Affects Our Lives
Climate Justice
Redlining & Climate Inequality
Social Inequality & The Climate
Renewable Energy & Inequality
Review & Credits
Credits

How can Daenerys Targaryen help us understand personal identity? Find out as Hank continues our exploration of personal identity, learning about Hume’s bundle theory and Parfit’s theory of survival through psychological connectedness.

This week we explore the final ethical theory in this unit: Aristotle’s virtue theory. Hank explains the Golden Mean, and how it exists as the midpoint between vices of excess and deficiency. We’ll also discuss moral exemplars, and introduce the concept of “eudaimonia.”

If you’ve been paying attention so far in this series, you’ve probably heard of benzene. This molecule is flat, cyclic, and belongs to a special class of compounds known as aromatics. In this episode of Crash Course Organic Chemistry, we’ll learn all about aromatic compounds, their properties, reactivities, and some of the most important examples, like benzene. We’ll also revisit our friend NMR, and hear about some dubious science history!

What's that smell? Smell's like Organic Chemistry! This week Hank talks about Aromatics and Cyclic Compounds, naming their substituents, resonance, and common reactions & uses.

Today Hank explores artificial intelligence, including weak AI and strong AI, and the various ways that thinkers have tried to define strong AI including the Turing Test, and John Searle’s response to the Turing Test, the Chinese Room. Hank also tries to figure out one of the more personally daunting questions yet: is his brother John a robot?