It's not even just about the 20th century or about humans, it's the entire history of the universe.

13.8 billion years ago - the big bang

4.5 billion years ago - earth was formed

3.5 billion years ago - cellular life emerges

2.1 billion years ago - multicellular life emerges

500 million years ago - cambrian explosion

178 million years ago - first mammals appear

55 million years ago - first primates appear

1.5 million years ago - homo habilis

200 thousand years ago - homo sapiens

70 thousand years ago - cognitive revolution

12 thousand years ago - neolithic revolution

500 years ago - scientific revolution

200 years ago - first industrial revolution

100 years ago - second industrial revolution

50 years ago - third indusrial revolution

Next up - fourth industrial revolution (AI revolution)