Human attention emerges gradually and transforms across the lifespan. In infancy, it begins reflexive— newborns briefly orient to stimuli like faces or voices through subcortical mechanisms, with very short spans of mere seconds. Through childhood and adolescence, attention span lengthens dramatically —sustained abilities improve with brain myelination and prefrontal efficiency. Efficiency peaks during young adulthood roughly 20s–30s, sustained attention often reaches its height ~75+ seconds in optimal states. In real-world optimal states flow states, deep work, or highly engaging activities like reading or problem-solving, many adults maintain focused engagement for hours — far beyond lab-measured bursts— though vigilance. From reflexive glances at birth to peak control in prime adulthood and adaptive changes in later years, attention evolves to support survival, learning, and emotional regulation until life’s end.