Evans said: "I think it was a doodle. I don't think it has any deep and meaningful religious significance."
"In this era of the Neolithic period they had a lot of time on their hands. It could show they were quite bored at times, but we don't know for sure."
"We do know when they weren't out harvesting or planting crops they had to find a way of killing time," Evans said.
The rock was discovered by business language teacher Susie Sinclair, 48, at Needingworth Quarry, alongside the river Great Ouse, near Over, early in July.
Sinclair was on a geological weekend course being run by the University of Cambridge's Institute for Continuing Education.
"I picked it up and showed it to our course leader Peter Sheldon who realised it was more significant than a fossilised worm," said Sinclair.
"He took a photo and sent it to Christopher Evans and the director of Stonehenge (a prehistoric monument located in the English county of Wiltshire) and that is when we realised it was serious," Sinclair added