And of all the artifacts that have aided cognition, the most important is the development of writing, or more properly, of notational systems: number systems, writing, calendars, notational systems for mathematics, engineering, music and dance.

FORBES: Magazine Article

So, good list, Forbes, but you left out the most important tools of all, the cognitive artifacts that have truly made us smart: writing and notational systems, objects of travel and information technology, which really picked up somewhere around the development of the telegraph, but could be argued to have developed earlier with the wide variety of signaling systems.

FORBES: Magazine Article