Neanderthals: Darwin knew about their existence
Darwin published his book On the Origin of Species three years after the discovery of the first Neanderthal skull. He knew about this discovery made in 1856.
The specimen was named Neanderthal, after the valley where it was found: the Neander Valley in Germany. We now know that those remains are 40,000 years old.
Darwin also knew about the discovery of stone tools made during the last Ice Age. These tools were at least 12,000 years old. The news rejoiced him; he was ecstatic. Finally, there was evidence contradicting what the ancient holy books suggested: that humans appeared 6000 years ago.