People across the world make similar facial expressions in various social situations, scientists have found.

An analysis of more than six million videos suggests substantial universality in how people express themselves in different scenarios.

However, researchers say the findings do not determine whether emotions themselves are universal.

More research is needed to get a fully unbiased view of how emotions are expressed in everyday life.

Alan Cowen from the University of California, and colleagues used a deep neural network (DNN) – a type of machine learning – to assess real-world behaviour and ascertain whether social contexts are associated with specific facial expressions across different cultures.

English-speaking people in India trained the DNN to identify 16 patterns of facial movement associated with distinct English-language emotion categories.

It then learned to cluster similar patterns as individual expressions, such as a smile, and assessed six million YouTube videos from 144 countries.

Researchers found that similar expressions often occurred in similar contexts worldwide.

For example, facial expressions often labelled as awe, contentment and triumph were associated mostly with weddings and sporting events across different regions.

Additionally, each type of facial expression had distinct associations with a set of contexts that were 70% preserved across 12 global regions, suggesting considerable universality across the world.

The researchers say their findings have important implications for understanding the origins, functions and universality of emotion.

Writing in the Nature journal, they add: “Our results reveal fine-grained patterns in human facial expressions that are preserved across the modern world.”

They continue: “Because these findings are based on online videos, they may have been influenced by cultural globalization, particularly through digital platforms.

“For example, people across the world may have adopted facial expressions from Western media.

“However, we do not see suggestions of a bias towards similarity with the West.

“Instead, we see greater similarity between neighbouring regions, which is expected if the videos are representative of local cultures as opposed to Western culture.”

The authors note that online videos do not provide an unbiased representation of everyday life.