"One big mystery that has been solved since I was a kid is “what killed the dinosaurs?” It turns out to be an asteroid that hit near the Yucatan, killing every single animal that couldn’t hide in a burrow on land and most of the big sea animals, too. You look at kids dinosaur books from the early 80s and there were a lot of different hypotheses. Another is “where did the moon come from?” Now everyone accepts it was created by another planet crashing into the earth, but in the 1980s there were several reasonable possibilities still being compared."
Humans can’t be used as an example. Unlike any other species, we go very far out of our way to make sure the weak and feeble-minded survive.