Modern humans and their hominid ancestors relied on chipped-stone technology for well over two million years and colonized more than 99 percent of the Earth's habitable landmass in doing so. Yet there currently exist only a handful of informal models derived from ethnographic observation, experiments, engineering, and "common sense" to explain variability in archaeological lithic assemblages.

Because the fundamental processes of making, using, and discarding stone tools are, at root, exercises in problem solving, Todd Surovell asks what conditions favor certain technological solutions....