 In the third edition of "On the Origin of Species" published in 1861, Charles Darwin added a "Historical Sketch" that acknowledged the ideas of Schaaffhausen.Many of his most important anthropological papers were collected and published in a book titled "Anthropologische Studien" (1885).Workmen quarrying the Feldhofer Grotte in the Neander Valley, near Düsseldorf in northern Germany, in 1856 unearthed human bones in the floor of the cave.