Why did our ancestors ditch the shell and start growing babies inside their bodies instead? In this episode of Big Ideas, from the team behind Deep Look, Niba zooms out to explore one of evolution’s ...

Eggs helped animals conquer land—but most mammals stopped laying them. Why is that? Why do most animals lay eggs, while humans and most mammals give birth to live young? In this episode of Big Ideas ...

Animals reproduce in a variety of fascinating ways. Some species, including humans and many other mammals, give birth to live young that develop inside the mother’s body. Others reproduce through less ...

Snakes, like most reptiles in the world, are oviparous. This means that rather than producing live young ones, the way mammals do, snakes produce an immature single cell — an egg. Most snakes follow ...