In general, people are living longer now . Discuss the causes  of this phenomenon. Use specific reasons and details to develop your essay.   It  is  the fact that  since humanity entered into  the 21st century, there has been  a significant rise in our life expectancy  in comparison with  that in the past. In other words , people are living longer nowadays. From my perspective , there are three main causes of this phenomenon.     First and foremost , the development of medical science can be considered as  a major factor in the development of human society. In the context of  accelerating dangerous diseases, medical technology which is in the form of  medicines, vaccines, or healthcare systems has been improved greatly to reduce mortality rates  and many life-threatening  diseases. For example, smallpox was widely regarded as  a pandemic  in the 1970s, but it has been eradicated from  the world just a few years ago.     Second of all , mechanization  brings about a comfortable life...