What if the story of life starts earlier than we thought? We break down LUCA, the Last Universal Common Ancestor, what it is, what it is not, and what new genetic clues suggest about life before LUCA. We also connect the origin of life to astrobiology, how scientists read exoplanet atmospheres using starlight, and why Earth’s changing atmosphere matters when searching for life beyond our planet. Then we jump into medieval history and the Black Death. New evidence suggests the plague’s spread ...