Novelist and blogger John Green muses about out how far back “back” goes in a vlog post that manages to inspire a fair mount of awe in just 3 minutes and 42 seconds:

The time spans he mentions are immense, and yet in the grand scheme of things they aren’t very much at all. From the first occupation of the Chauvet cave until today is less than six one-hundredths of one percent of the time since the end of the Mesozoic, the Age of the Dinosaurs. And from the end of the Mesozoic until today is less than 1.5 percent of the lifetime of the Earth. (Feel free to check my arithmetic.)

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