Mass extinctions provide important clues about evolutionary processes, since they typically drive evolution forward. Despite how important it is to know about prior extinctions in Earth’s history, scientists actually know very little about them—they know that they happened, but they don’t know
why. Five of these extinctions have been mass extinctions that wipe out most life on Earth, further stressing how perilous the continued existence of our species is. The fact that we’ve lasted so long is very lucky, especially as we have insufficient knowledge about what triggers mass extinctions in the first place.