[Note: This is (roughly) the text of a talk I delivered at TEDxWHU on the 4th February 2017. A video of the talk should be available within a few weeks.]
There is a cave about 350km from here, in the Swabian Jura. It is called the Hohle Fels (this picture is the entrance to it). Archaeologists have been excavating it since the late 1800s and have discovered a number of important artifacts from the Upper Paleolithic era. In June 2005, they announced an interesting discovery.