Over the past 150 years there has been a huge increase in population. One reason is that medicine and health care have advanced considerably and sanitation has become better than before. They have caused fewer infant deaths and more people living longer. Another reason is that improved farming methods have produced more and better food so that people would not need to worry about starving to death. Economy is another reason that causes a huge increase in population. If people drawn a large income, they would lead a better life than dying of cold or starvation. It is for all these reasons and more that has led to the population increase.
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