The Polyvagal Theory helps us understand how cues of risk and safety, which are continuously monitored by our nervous system, influence our physiological and behavioral states. The theory emphasizes that humans are on a quest to calm neural defense systems by detecting features of safety. This quest is initiated at birth when the infant needs for being soothed are dependent on the caregiver. The quest continues throughout the lifespan with needs for trusting friendships and loving partnerships to effectively co-regulate each other. The Polyvagal Theory proposes that through the process of evolution, social connectedness evolved as the primary biological imperative for mammals in their quest for survival. Functionally, social connectedness enabled proximity and co-regulation of physiological state between conspecifics starting with the mother-infant relationship and extending through the lifespan with other significant partners. The theory explains why feeling safe requires a unique set of cues to the nervous system that are not equivalent to physical safety or the removal of threat. The theory emphasizes the importance of safety cues emanating through reciprocal social interactions that dampen defense and how these cues can be distorted or optimized by environmental and bodily cues.