Discussing Cause - 1 - revised

     Over the past 150 years there has been a huge increase in population.  According to scientists’ researches, there are a lot of reasons for it.  First of all, medicine and health care are progressive.    In the past, there is a great deal of diseases that doctors can’t remedy.  Now, medicine has made great progress.  Therefore, the mortality is decreasing.  Second, we have better sanitation.  With health concepts, modern people care hygiene, including food hygiene, personal hygiene, environmental sanitation, and so on.  To maintain good health habits, you can avoid falling ill.  Third, people improved farming methods that produce more and better food.  There are more people discovering better farming methods, and manufacturing abundant food.  Last but not the least, fewer infant deaths and more people living longer lead to a huge population.  Hospital care is complete, so the infant mortality decreases.  And the old may take plenty of medicines to keep their life.  To sum up, the population suddenly increase is because the technology is advancing.