Our capability for affective awareness and emotional expression is influenced by the evolutionary state of our brain, autonomic nervous system, and pathways through which they communicate. These capabilities are key to social communication with other humans.
Of course, the systems underlying our sociality are tightly interwoven with neural circuits involved in survival, such as homeostatic, endocrine, and autonomic processes. Visceral homeostatic maintenance is vital for survival as well, therefore our social communication circuits are deeply dependent on those that regulate basic visceral homeostasis.
It’s evident from evolution as well that the autonomic nervous system is important for how we experience affect, behave socially, and communicate vocally and visually. This can be seen through polyvagal theory, where as mammals evolved from their reptilian ancestors, the vagal efferent pathway arose to produce more and more sophisticated behavioral functions – from immobilization and death feigning in the unymelinated vagus to advanced social communication, self-control, and calming in the modern myelinated vagus.
This vagal pathway serves as a link between autonomic nervous system regulation and brain-stem-related cranial nerve control of facial muscles and expression, and social communication.