Why do different dialects develop?Are they important to a cu

Why do different dialects develop?Are they important to a culture?Why or why not?
写一段英文短文，明天口语考试，大侠们要给力啊

As the diffrent people live in diffrent places and in diffrent times ,they forms the different languages ,just like dialects .With the transmiting of some generations to generations ,various dialects develop instead of vanishing the river of times .
No doubt that dialects are vital to culture .They belong to some parts of culture .Through learing the dialects ,we can grope for the culture of the group that speak these dialects .As we konw ,learning culture is important to us ,the reasons as follow:
f1.With the growth of globalization ,the whole world is associated together .Learning different cultures can facility the mutual understand of the whole world ,thus lessening the culture shock at most.
2.Learning different cultures can help counries learn the other counries' technology and scenice more easily ,so that it can accelerate the pace of development .
3.Learning different cultures can make sense to avoid some misunderstandings and misleadings during interactions and communcations to some degree.
4.When based on the fully understanding of culture ,it is more easier for us to study various aspects of some counries,such as languages .
Thus ,they are indispensible to a culture .