"The 'up' gesture looks just like if you find a human child asking to pick them up," Gillespie-Lynch told LiveScience.
The baby girl used more gestures overall and developed gestures - such as waving bye-bye, shaking the head and nodding - that the apes did not demonstrate.
The girl tended to use more gestures for showing things to caretakers, whereas the apes relied more on reaching gestures. Together, the findings suggest the human child was more focused on sharing her experience with others, whereas the apes were using gestures more instrumentally to get what they wanted.
As they grew older, the species' trajectories diverged. All the infants gradually shifted to using more symbolic words, but the child's shift was much more dramatic than the apes'. And from the start, the little girl vocalized more than the apes did.
Because gesture played an early role in communication in all of the babies, it probably also played a similar role in a common ancestor, Gillespie-Lynch noted.
"So we're getting an idea of what our common ancestor was like in terms of how that ancestor might have been able to communicate," she said.