Wait But Why offers a crudely-drawn-yet-still-awesome history of evolution, taking us back through time:
I don’t know what to tell you. This is a part of your lineage.
I want you to pause and just ponder for a second that I’m not inventing silly shit here — if you take your father, and your father’s father, and do that 435,000,000 times, you’ll end up at a jellyfish. Evolution is boggling.
One of the takeaways is still awe-inspiring every time I hear it (emphasis theirs):
How incredibly unlikely it is that you exist. Going back to the first particle of life, there are over a trillion fathers and father’s fathers that eventually ended with your parents conceiving you. And if any one of those fathers (or mothers) had died before reproducing — if any of the millions of fish in your line had been prematurely eaten, if any of the millions of rodents in your line had been crushed by a falling tree as a baby — you would not exist. Maybe someone similar to you — but not you.
If you spot any mistakes in the explanations, let them know!