> Gossip, according to Robin Dunbar in his book Grooming, Gossip and the Evolution of Language, does for group-living humans what manual grooming does for other primates — it allows individuals to service their relationships and so maintain their alliances on the basis of the principle: if you scratch my back, I'll scratch yours. Dunbar argues that as humans began living in increasingly larger social groups, the task of manually grooming all one's friends and acquaintances became so time-consuming as to be unaffordable.[51] In response to this problem, humans developed 'a cheap and ultra-efficient form of grooming' — vocal grooming. To keep your allies happy, you now needed only to 'groom' them with low-cost vocal sounds, servicing multiple allies simultaneously while keeping both hands free for other tasks. Vocal grooming then evolved gradually into vocal language — initially in the form of 'gossip.'[51] Dunbar’s hypothesis seems to be supported by the fact that the structure of language shows adaptations to the function of narration in general.[52]
> Critics of this theory point out that the very efficiency of 'vocal grooming' — the fact that words are so cheap — would have undermined its capacity to signal commitment of the kind conveyed by time-consuming and costly manual grooming.[53] A further criticism is that the theory does nothing to explain the crucial transition from vocal grooming — the production of pleasing but meaningless sounds — to the cognitive complexities of syntactical speech.
https://en.wikipedia.org/wiki/Origin_of_language#The_gossip_...