Somewhere on the timeline between the long run of the Oldowan and the more rapid rise of Acheulean technologies, language (or what’s often called protolanguage) likely made its first appearance. Oren Kolodny and his co-author, Shimon Edelman, a professor of psychology at Cornell University, say the overlap is not a coincidence. Rather, they theorize, the emergence of language was predicated on our ancestors’ ability to perform sequence-dependent processes, including the production of complex tools.