Was it because:

1) humans killed them;

2) they couldn't hack the climate after the Ice Age ended; or

3) an exploding comet ignited continent-wide wildfires, sent hundred-mile-an-hour winds and tornadoes howling across the land, and shattered the North American ice sheet, while also maybe gouging out the Great Lakes?

Let's talk about option number three.

The idea that a comet struck Earth 12,900 years ago, at the beginning of a strange interlude of climate cooling called the Younger Dryas was first proposed in 2007. In the bitter scientific debate that has flared sporadically ever since, the latest evidence includes:

Some opponents of the hypothesis—and there are many—want so badly for it to go away that they have attempted to declare it