Babies begin to "talk" at just a few months old using gestures whose meaning is often overlooked by parents, say scientists.
The subtle "micro-behaviours" are said to be an early demonstration of attention-sharing - a key element of human language.
Humans are the only species to communicate by sharing their focus of attention, according to experts. Examples include following another individual's gaze or showing someone an interesting object.
Until now researchers have mostly focused on infants sharing attention by pointing with their index finger, a behaviour that usually appears at around 10 to 12 months of age.
The study, which involved filming 24 boys and girls aged 10 months as they played with a selection of toys, identified earlier forms of attention sharing based on less obvious "showing and giving" gestures.
The team of social scientists found that the gestures were strong predictors of how often infants used pointing when they were older.
Despite the behaviours being widespread, they often left parents puzzled.
Professor Elena Lieven, director of the Economic and Social Research Council (ESRC) International Centre for Language and Communicative Development at the universities of Manchester, Liverpool and Lancaster, said: "Our research demonstrates that babies may be doing more to communicate than many of us usually assume, and at an earlier age.
"By understanding these early behaviours, parents have a great opportunity to help support their children's later language development. Understanding babies' gestures could be just as important as understanding their early language."
As part of the study, the researchers analysed the responses of parents and caregivers to the babies' attention-sharing gestures.
The findings were presented at an ESRC Festival of Social Science event at the University of Manchester.
Prof Lieven added: "The ability to share and direct attention is an essential basis for typical language development, and others have found that it is often impaired in children on the autism spectrum.
"Our findings provide useful guidance to both researchers and caregivers in the identification of infants' early attempts to communicate about objects with their caregivers, and highlight the need for greater study of these early pre-linguistic behaviours."