There are 42 muscles in the human face. Scientists believe that with those 42 muscles, humans can only make four recognizable facial expressions.
According to a new study released in 2014, scientists from the University of Glasgow studied human facial muscles in relation to the number of faces an average human makes. People make faces for a variety of reasons, ranging from happiness to disgust. The results from this study show that the four different facial expressions humans make come from specific sets of muscles. Variations of these faces, such as the differences between anger, fear and disgust, come from different muscles and are often very similar.