Finding humanly made stone axes in the same layers as the bones of extinct European animals like hippopotamus, elephant, and saber-toothed tiger implied that humans were older than the Biblical chronology implied.

At first, scientists ignored these discoveries. By 1859, there were too many occurrences for the association to be denied any longer. British archaeologist John Evans visited quarries along France's Somme River and himself pulled stone axes from alongside hippopotamus bones. He announced that humans had lived much earlier than 6,000 years ago.