Nasal mucus is very important to our health – and actually kind of magical. There’s a lot going on in our noses all the time that we don’t appreciate. Where do boogers come from? Why does your nose run when you’re out in the cold? Why does your nose get stuffy when you’re sick?

Can you tickle yourself? Probably not. Almost everybody is ticklish, but what’s happening to us is a bit of a mystery.

See omnystudio.com/listener for privacy information.

Can you tickle yourself? Probably not. Almost everybody is ticklish, but what’s happening to us is a bit of a mystery. We talk to a neuroscientist about how our skin and brain are connected, and a paleoanthropologist about why it make us a laugh.

We’ve gotten a lot of questions about bridges and tunnels: How do bridges stay up? How are tunnels built? How do they build bridges over water? How do they put tunnels underwater? To answer these questions we’re staging a little friendly competition: bridges vs. tunnels!

See omnystudio.com/listener for privacy information.

We’ve gotten a lot of questions about bridges and tunnels: How do bridges stay up? How are tunnels built? How do they build bridges over water? How do they put tunnels underwater?

To answer these questions we’re staging a little friendly competition: bridges vs. tunnels!

We’ll find out how they’re built, where they’re found in nature, and what they may look like in the future. Plus: A visit from our friendly neighborhood robot.

SPOILER ALERT: Click here to learn more about this episode’s mystery sound.

Music in this episode by Podington Bear via Creative Commons.

Plus: Check out a tunnel boring machine in action!