Reverse engineering ancient toolmaking practices provides a sort of time machine that takes scientists back to extract ideas about the cognitive abilities of our relatives from eons past. Researchers at Emory University teach students how to make two classes of stone age implements—Acheulean and Oldowan technologies—and observe what’s happening inside their skulls using brain scanners. The differences in scanner activity seen in the more advanced Acheulean technology may provide clues as to how brains evolved to become capable of fabricating more sophisticated tools. Anthropology professor Dietrich Stout discusses his work in experimental archeology in the April Scientific American.