c. 1200, talken, probably a diminutive or frequentative form related to Middle English tale "story," and ultimately from the same source as tale (q.v.), with rare English formative -k (compare hark from hear, stalk from steal, smirk from smile) and replacing that word as a verb. East Frisian has talken "to talk, chatter, whisper." Related: Talked; talking.
To talk (something) up "discuss in order to promote" is from 1722. To talk shop is from 1854. To talk turkey is from 1824, supposedly from an elaborate joke about a swindled Indian.
Phrase talking head is by 1966 in the jargon of television production, "an in-tight closeup of a human head talking on television." In reference to a person who habitually appears on television in talking-head shots (usually a news anchor), by 1970. The phrase is used earlier, in reference to the well-known magic trick (such as Señor Wences's talking head-in-the-box "Pedro" on the "Ed Sullivan Show"), and to actual talking heads in mythology around the world (Orpheus, Bran).