Final answer:
Life expectancy has greatly improved due to three main factors: the provision of clean water and efficient waste management, better public health practices, and significant advances in medical technology like vaccines and antibiotics.
Step-by-step explanation:
The significant increase in life expectancy can be attributed to a combination of factors. First, the development of infrastructure for supplying clean water and efficient waste management systems dramatically reduced the spread of diseases.
Second, there was a shift in public behavior towards better health practices, such as elevated hygiene standards like hand-washing, and a decrease in tobacco smoking. Third, and crucially, were advances in medical technology, notably the development of vaccinations and antibiotics, which have played a pivotal role in managing infectious diseases.
Medical advancements such as the creation of immunizations against diseases like diphtheria, cholera, and yellow fever, particularly between the years 1890 and 1930, led to vast improvements in public health. The discovery and subsequent widespread use of penicillin in 1941 and other antibiotic drugs marked a revolutionary step in controlling infectious diseases.
Moreover, drugs that address high blood pressure have also contributed significantly to the increased life expectancy in recent decades.