A team of researchers have said that Chimpanzees too have different smiles like humans but they do not need to make the accompanying sound.

The team said that it has found that chimpanzees have the same types of smiles as humans but they are able to produce them silently. Experts said that the ability to produce facial expressions and vocalizations is an important part of human interactions. However, there is very little research into the facial expressions and vocalizations of other species.

Dr Marina Davila-Ross of the University of Portsmouth, UK, lead author on the study, said, "Humans have the flexibility to show their smile with and without talking or laughing. This ability to flexibly use our facial expressions allows us to communicate in more explicit and versatile ways, but until now we didn't know chimps could also flexibly produce facial expressions free from their vocalizations."

The team studied if chimpanzeesproduce the same types of facial expressionswith and without accompanying vocalizations like humans. They recorded videos of 46 chimpanzees at the Chimfunshi Wildlife Orphanage in Zambia. They used ChimpFACS, a facial action coding system designed for chimpanzees and measures the facial movements.

Co-author Prof Kim Bard, also from the University of Portsmouth said that the coding system allowed them to record subtle facial movements and compare those with human movements. They found that chimpanzeeshave the same 14 open-mouthed facial expressions

The study was published in the journal PLoS ONE.