Old World rats and mice

I. The Black Death (1347) A. Causes: 1. Bubonic plague was carried by fleas on Asian black rats and brought to Europe on ships returning from Asia 2. Overcrowding in cities and homes facilitated the spread of the disease Many aristocratic families slept in one room and many prosperous peasant families slept in one bed for warmth; less prosperous peasants were even worse off 3. Poor sanitation in cities: garbage-filled streets, human excrement, and dead animals 4. Widespread malnutrition prior to the plague led to poor health (e.g. lower immune systems) that made people more susceptible to the disease 25% harvests in early 14th century were poor as torrential rains destroyed wheat, oats, and hay crops; some instances of cannibalism occurred