"perished.1 Andrea's story, of parents whose last heroic act is to ensure their child's survival, captures a moment of almost mythic courage. Without doubt such incidents of parental sacrifice for their progeny have been repeated countless times in human history and prehistory, and countless more in the larger course of evolution of our species.2 Seen from the perspective of evolutionary biologists, such parental self-sacrifice is in the service of "reproductive success" in passing on one's genes to future generations. But from the perspective of a parent making a desperate decision in a moment of crisis, it is about nothing other than love. As an insight into the purpose and potency of emotions, this exemplary act of parental heroism testifies to the role of altruistic love--and every other emotion we feel--in human life.3 It suggests that our deepest feelings, our passions and longings, are essential guides, and that our species owes much of its existence to their power in human affairs. That power is extraordinary: Only a potent love--the urgency of saving a cherished child--could lead a parent to override the impulse for personal survival. Seen from the intellect, their self-sacrifice was arguably irrational; seen from the heart, it was the only choice to make. Sociobiologists point to the preeminence of heart over head at such crucial moments when they conjecture about why evolution has given emotion such a central role in the human psyche. Our emotions, they say, guide us in facing predicaments"