Play Four

It's commonly known that a single asteroid set off the dinosaurs' extinction. Even more destructive than its impact was the chain of events it set into motion.

How a Single Asteroid Wiped Dinosaurs Off This Planet (1:14)

Thousands of massive stone monuments, known as Moai, preside over Easter Island. The way they were carved, using only stone tools, seems unfathomable.

How Were Easter Island's Gigantic Statues Actually Carved? (4:11)

Green tree vipers can kill in the dark. With special heat-sensing abilities, they can find prey that's all but invisible.

A Pit Viper's Sixth Sense (2:03)

With the development of better flight technology, commercial air travel received an unprecedented boom in the 1960s. But to fully sell the glamor of flying, the airlines needed these women on board.

Air Travel Was a Party, and They Were the Hosts (2:57)