Why do we settle for one person when our biology screams for variety? Dr. Anna Machin exposes love as a form of 'biological bribery'—a high-stakes neurochemical game designed to force us into the difficult work of cooperation. From the 'genetic sniffer' women use to pick mates to the addictive opiates that keep us bonded for decades, we explore the machinery of the human heart through the lens of evolutionary anthropology.