Final answer:
Increased human lifespan in the West is largely due to sanitation infrastructure, changes in public behavior, and advancements in medicine, including immunizations and antibiotics.
Step-by-step explanation:
The increase in human lifespan in western countries is attributable to several key factors. Sanitation improvements, such as systems for providing clean water and disposing of human waste, have been instrumental in reducing the transmission of diseases. In addition to infrastructure improvements, there have been significant changes in public behavior that have bolstered health outcomes. Practices such as boiling baby's milk bottles, hand washing, and food protection strategies became widespread, drastically reducing the incidence of disease. Later behavioral shifts like the decrease in tobacco smoking and increased precautions against sexually transmitted diseases also contributed to better health.
The advancements in medicine have played a significant role in extending lifespans. The development of immunizations for diseases such as diphtheria, cholera, pertussis, tuberculosis, tetanus, and yellow fever was a major breakthrough. The discovery of penicillin led to a series of antibiotic medications that controlled infections. Furthermore, in recent times, the introduction of drugs to manage high blood pressure has significantly increased longevity. These medical breakthroughs, together with public health initiatives, have had a dramatic impact on life expectancy.