Researchers studied almost all of the available children in three communities in China, Fiji and Ecuador from ages 19 months to about 5 years.
"The findings may shed light on the social abilities that differentiate us from our closest living relatives, chimpanzees," said study author H Clark Barrett, an anthropologist at the University of California, Los Angeles.
They used a form of the false-belief test on 91 kids, one of the few cognitive tasks that young children, but not primates, can do, LiveScience reported.
Humans are very good at inferring other people's mental states: their emotions, their desires and, in this case, their knowledge, Barrett explained.
In the classic test of children's understanding called the false-belief task, one person comes into a room and puts an object (such as a pair of scissors) into a hiding place.
A second person then comes in and puts the scissors into his pocket, unknown to the first individual. When that first person returns, someone will ask the child, "Where do you think the first person will look for the scissors?"
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The task is tricky because the children need to have a theory of mind, or an ability to understand other people's perspectives, in this case that of the individual who didn't see the scissors being retrieved by another.
By ages four to seven, most children in Western countries can answer that the first person will look in the original hiding place, because the individual doesn't know the scissors have moved.
But children across the globe tend to give that answer at different ages.
However, past work showed that if researchers don't ask babies the question, but instead follow the infants' eye movements, the children seem to understand the concept much earlier.
Barrett and his colleagues wondered whether cultural differences in dealing with adults could be obscuring the amazing cognitive leap children were taking.
The team created a live-action play with a very similar set-up to the classic false-belief test: A man leaves some scissors hidden in a box, while another person comes in and puts them into his pocket.
Researchers noted that youngsters consistently looked at the box, showing that the little ones expected the first man to search for the scissors where he had left them.
The findings show that children develop this mind-reading ability of sorts years earlier than previously thought, and that this development looks the same across many different cultures, researchers said.