Which technological advancement contributed to the decline in mortality rates in the 1800s?

The advancement in scientific understanding during the 1800s played a significant role in reducing mortality rates, particularly through the development of germ theory and improvements in public health practices. Scientists began to connect specific pathogens to diseases, which led to better sanitation, hygiene, and practices such as sterilization in medical settings. This awareness of the causes of illnesses allowed for more effective responses to epidemics and improved the overall health of populations.

While vaccinations, advancements in agriculture, and the steam engine had their own impacts, it was the shift in scientific understanding that directly informed methods to combat disease and improve public health outcomes, thereby leading to a notable decline in mortality rates during this period.