Sociologists disagree on whether the concept of childhood existed before the 1600s. Philippe Aries and others argued that childhood was not recognized as distinct from adulthood, while Linda Pollock and others argue parents have always been emotionally invested in their children. Pollock cites diaries showing parents deeply grieved child deaths, suggesting childhood has long been recognized. The debate centers on whether parental care and the view of children have fundamentally changed over time.