Human face conveys happiness in different ways, say scientists

While disgust needs just one facial expression to get its point across throughout the world, happiness has 17 -- a testament to the many varied forms of cheer, delight and contentedness, finds a study.

On the other hand, to convey fear humans use three expressions, four to convey surprise, and five each to convey sadness and anger.

The researchers explained that the differences in how our faces convey happiness can be as simple as the size of our smiles or the crinkles near our eyes.

"This was delightful to discover, because it speaks about the complex nature of happiness," said Aleix Martinez, Professor at The Ohio State University. "Happiness acts as a social glue and needs the complexity of different facial expressions; disgust is just that: disgust," Martinez said.

The study showed that humans can configure their faces in thousands and thousands of ways to convey emotion -- from anger to sadness to riotous joy -- but only 35 expressions are actually similar across cultures. 

For the study, published in the journal IEEE Transactions on Affective Computing, the team assembled a list of 821 English words that describe feelings and then used those words to mine the Internet for images of people's faces. 

The words were translated into Spanish, Mandarin Chinese, Farsi and Russian, and plugged into search engines popular in 31 countries across North America, South America, Europe, Asia and Australia to download an equal number of images. 

They found approximately 7.2 million images of facial expressions across a variety of cultures. 

Based on computer algorithms, the team found that the human face is capable of configuring itself in 16,384 unique ways, combining different muscles in different ways. 

 The researchers took the 7.2 million images their searches yielded and sorted them into categories, looking for those that expressed emotion across cultures. They found only 35.