The 1918 to 1920 influenza pandemic infected an estimated 500 million people, a third of the global population, and killed the healthy as readily as the frail. This episode debunks the myth of its Spanish origins, tracing how wartime censorship manufactured the misleading name while the real story unfolded across military camps and trenches.

Drawing on phylogenetic research and primary sources, the discussion follows the breadcrumbs to Kansas and the staging camps of France, then explains how the conditions of World War I inverted natural selection to favor a lethal strain. It explores the cytokine storm that turned strong immune systems deadly, the climate anomaly that worsened the toll, and the 2005 reconstruction of the virus from permafrost.

• Why neutral Spain became falsely branded as ground zero
• How trench logistics  ...