The reason the cardiologist’s symbol doesn’t look anything like an actual heart is that it isn’t one. It’s a silphium seed pod — silphium being the contraceptive-and-aphrodisiac plant the Greeks of Cyrene grew on coins, then over-harvested into extinction by the second century AD. Botanist Mahmut Miski has spent the last decade arguing that Ferula drudeana, growing on a single Turkish slope, is silphium’s surviving cousin, and that cold-stratification can bring the lineage back. Maria Popova traces the whole 2,400-year arc.