Humans, like all animals, inherit an evolved nest for their young that optimizes normal development. Humanity spent 99% of its existence in societies that provided the nest, which nourishes practical wisdom that guides sociality and morality, and fosters flourishing. A species-atypical nest, common in civilized nations, is toxically stressful. It undermines neurobiological structures that undergird self and sociality, leading to a persecutorial superego with a focus on self-preservation. Morality becomes self-protectionism – forms of self-preservation that are compulsively externalizing, internalizing, or dissociative – and ecologically destructive. Sociopathy becomes widespread and intergenerational. But cultures can change. Restoring the evolved nest can revive humanity’s potential.