The valued ability to speak effectively and persuasively dates back to

The answer for this question is:  3200 B.C.E
During this period of time, Civilizations started to recognize organizational activities and the basic structure of Governance.
This condition make someone that has the ability to speak effectively and persuasively could get people to do his/her bidding and they could obtain power within a certain society.

During the paleolithic, hominins grouped together in small societies such as bands, and subsisted by gathering  plants  and fishing, hunting or scavenging wild  animals. the paleolithic is characterized by the use of knapped stone tools, although at the time humans also used  wood  and bone tools.