This clip explains the known history of the Neanderthals, who were the closest relatives to the modern human in the family tree. They lived about 400,000 - 40,000 years ago. This clip discusses their habitat and the evolutionary adaptations that may have allowed them to survive a cold, glacial ecosystem. It then speculates the leading theories surrounding their mysterious disappearance.
Charlie explains radiocarbon dating and how it is used to calculate the approximate age of an object. To make his explanation more concrete, he uses an analogy involving a refrigerator and the number of ice cubes in it.