Imagine you're a time traveler whose time machine has functioned somewhere in Earth's past — after humans have evolved but before they've, say, invented language or agriculture or any of the other pillars civilization was built upon. How might you try to kickstart that process with all these hominids you keep meeting? And how would you avoid rebuilding civilization with all of the flaws of our current world? That question is the basis of Ryan North's new book How to Invent Everything, a hugely enjoyable book that really does come close to achieving what's promised in the title. (You'll even learn how to invent a computer using a river!) North is probably best known to this point as the writer of comics like Adventure Time and The Unbeatable Squirrel Girl, as well as the creator and writer of Dinosaur Comics, a webcomic that has run since 2003 using the exact same clip art (of dinosaurs, of course) in all six panels for 15 years. Todd and North talk about the foundations of society, what you learn writing a comic whose art doesn't change from day to day, and why the best meals are sometimes those you can never have again. Then: Todd is joined by astronauts Mae Jemison and Leland Melvin to talk about leaving behind Earth's orbit — and how we just might find humanity's future on our next-door neighbor Mars.