The importance of children's earliest years has long been recognized, but our understanding of the underlying science has taken a significant leap in the past decades. Studies regularly document the effects that a child's earliest experiences can have on later life and adult health. There is a growing consensus among experts that a key mechanism linking childhood adversity to later health and well-being is the stress caused by early negative experiences. These early negative experiences manifest in neglect, emotional and physical abuse, and excessively harsh parenting.