Is There Evidence of Mass Extinctions on Earth?

One good way to predict the future is to see if this has happened at regular intervals in the past. There's two categories of evidence that people have looked at to see if there are patterns. One is biological and the other is geological. I think we have this sort of nice notion that these mass extinctions don't really happen because we have not been direct witnesses to a mass extinction in our human species lifespan. But yeah, they do happen with, you know, some regularity, not too often, but it's something that is hard to think of happening to us due to how much we like living on the planet.