Facial expressions are fundamental nonverbal communications, using muscle movements to convey an individual's emotional state to observers and playing a vital role in social interaction across humans and many other mammals. These expressions can be voluntary, driven by social conditioning and a cortical brain pathway, or involuntary, believed to be innate and following a subcortical route, evident in infants and blind children. The amygdala is critically involved in facial recognition, processing visual information through subcortical pathways. Interestingly, due to the right brain hemisphere's specialization for emotional processing, expressions often appear stronger on the left side of the face, especially for negative emotions. While crucial for communication, including sign language, the universality of facial expressions across all human cultures remains a debated topic.