For all of recorded history, people have looked more or less the same: two eyes, two ears, a nose, a mouth, a head sitting atop an oblong body with two arms and legs.
As unlikely as it sounds, life forms from spiders to spider monkeys belong to the same family tree.
Even fungus merits an invitation to the family reunion.
Furthermore, many animals — giant ground sloths in South America, monstrous reptiles in England — had gone extinct long ago.
So even if people continued to look to the Bible for spiritual guidance, they began to doubt it was a literal account of the history of life on Earth.
He suggested that organisms could acquire needed characteristics for changing environments, an idea that has been laughed off by history, but his views were actually more nuanced than modern accounts usually relate.
Cuvier, regarded as the greatest comparative anatomist of his day, disdained Lamarckian "transmutation" but that didn't keep others from considering it, such as Erasmus Darwin, Charles Darwin's grandfather.
But if you were to go back further in time, a couple million years before anybody figured out how to write, your ancestors would still have two eyes, two ears, a nose, a mouth, a head sitting atop an oblong body with two arms and legs. If you went further back in time, the arms would be front legs.
Even further back in time, the fur would be scales.
Only later came Noah's Flood, which was held responsible for depositing all those weird remains, like shells, in rocks on top of mountains.
If that actually happened, human remains should have appeared in the oldest rocks at the bottom of the heap, but they didn't. The oldest layers of rocks held different creatures, and the further down in the heap one looked, the weirder the creatures got.
A simple way to think of evolution is "descent with modification" — over many generations, organisms change into something different.