Now life expectancy has prolonged drastically.  There are lots of factors of this tendency and among them, development of science and technology is the influencial thing. 

 

  Development of science, especially medicine has brings precious effective remedies of several serious diseases, which had killed many people.  For instance, the descovery of the cause and following specific medicine of tuberculosis which was the staple cause of people's death, save people and prolong our life.  We succeed in eradicating smallpox.  Penicillin or other antibiotics save lots of patients suffering from viral diseases.  In this way, development of medicine change the death sentence of patients having termical diseases into hopeful future.

 

  Advanced technology has enabled us to gain enough food, which prevent or at least reduce the seriousness of famine and drought.  We can raise larger amount of crops, vegetable, and livestock by well-developed agricultural technology.  We can yield several strong breeds.   Well-established transportation systems have brought sufficient foods to starving people in developing countries or affected areas.  Therefore, there are fewer people dying of starvation.

 

  In general, we have lived longer than ever before because of the development of technology.  As I mentioned before, this groundbreaking change have provided us for specific medicine of "former " devastating ailments and sufficient food.  Therefore, it is, I believe, the most effective cause of prolonged life expectancy.