Hank and physiologist Jon Harrison discuss the question of insect size and major theories that attempt to explain why there is a limit to how large insects can get with current conditions on Earth.

Feeling motivated? Even if you are, do you know why? The story of Aaron Ralston can tell us a lot about motivation. In this episode of Crash Course Psychology, Hank tells us Ralston's story, as well as 4 theories of motivation...

Did humans evolve from monkeys or from fish? In this enlightening talk, ichthyologist and TED Fellow Prosanta Chakrabarty dispels some hardwired myths about evolution, encouraging us to remember that we're a small part of a complex,...

Our next stop in our tour of the ethical lay of the land is utilitarianism. With a little help from Batman, Hank explains the principle of utility, and the difference between act and rule utilitarianism.

A barometer is an instrument that measures air pressure, allowing weather forecasters and scientists to better predict extreme weather events. Despite its incredible usefulness, inventing the barometer was no walk in the park. Asaf...

You might have heard that Earth is due for a complete flip of its magnetic field. And while our planet does have a history of this behavior, predictions of when it might happen are too complex to estimate a date for.

Improve your understanding of molecular properties with this lesson on the fascinating property of chirality. Your hands are the secret to understanding the strange similarity between two molecules that look almost exactly alike, but are...

Water covers over 70% of the Earth, cycling from the oceans and rivers to the clouds and back again. It even makes up about 60% of our bodies. But in the rest of the solar system, liquid water is almost impossible to find. So how did our...

The sky is blue, but according to whom? Could the rules of our language affect the way we perceive color?

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

I bet you've heard about the birth order cliche: The oldest child is responsible, the middle one is a rebel, and the youngest is spoiled. This stereotype might apply to you and your siblings, but is it universal?

in 19th-century England, scientists were figuring out that certain parts of our brains were connected with certain parts of our bodies- but they came up with some terrible and misleading ideas that spread without rigorous scientific...

Ever wonder how lightning works? Scientists are still figuring it out, but what we do know is fascinating. Learn about positive and negative lightning, red sprites, blue jets, and ball lightning in this episode of SciShow!

If it seems like friendships formed in adolescence are particularly special, that's because they are. Childhood, adolescent, and adult friendships all manifest differently in part because the brain works in different ways at those stages...

In which John Green teaches you about population. So, how many people can reasonably live on the Earth? Thomas Malthus got it totally wrong in the 19th century, but for some reason, he keeps coming up when we talk about population. In...

Plato and Aristotle: Crash Course History of Science #3

Evolution is particularly vulnerable to misunderstandings around the scientific language. SciShow clears up some confusing language!

Hank gets real with us in a discussion of evolution - it's a thing, not a debate. Gene distribution changes over time, across successive generations, to give rise to diversity at every level of biological organization.

The next entry in our parade of heroes is Rama, the protagonist of the Ramayana, one of India's oldest stories. We're going to be talking about Rama's importance to Hindu culture, and how Rama fits into Campbell's idea of the Hero's...

Why strings? What are they made of? How did physicists even come up with this bizarre idea? And what's all this nonsense of extra dimensions?

Researchers have made some unexpected readings of mysterious particles called muons, which may make us reexamine the Standard Model in physics.

Remember how Darwin and Mendel lived around the same time, but everyone forgot about Mendel until 1900, and even then biologists saw Darwinism and Mendelism as two competing grand theories about how life works?

Well, in this episode...

It's all about the SUPER TINY in this episode of Crash Course: History of Science. In it, Hank Green talks about germ theory, John Snow (the other one), pasteurization, and why following our senses isn't always the worst idea.

It's Earth Science time!!!! In this field, natural philosophers were asking questions like, what’s up with fossils? Are they the remains of extinct organisms? Or are they so-called “sports of nature”—rocks that just happen to look like...