Researchers, including those from Universidad Autonoma de Madrid in Spain and Boston College in the US, carried out facial recognition studies on native people living in New Guinea and the difference they found in one facial expression from most other people in the world.
For nearly a half-century, scientists have accepted the conventional view that the facial expressions used by humans have the same meanings regardless of location or culture, due to work done by psychologist Paul Ekman in the 1960s.
This culture has managed to exist without interacting with others for hundreds of years.
However, rather than simply testing the people right away, the researchers immersed themselves in the culture, learning both their language and their ways.
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They asked some of the young people to sit down with them to look at photographs of people with various expressions on their faces, 'Medical Xpress' reported.
The Trobrianders viewed all of the expressions the same way as westerners, with one notable exception - photos showing wide-eyed people with mouths slightly agape were viewed as threatening.
The team said this finding indicates that human facial expressions are not quite as universal as has been assumed.
The study was published in the journal Proceedings of the National Academy of Sciences.