"Copy from one, it's plagiarism; copy from two, it's research. "
Crisp well written text is important in many situations; it gives the reader a positive first impression. If you are one of those who fear the comma and loathe the sub clause help is at hand.
Writing was developed independently in Egypt, Mesopotamia, China, and among the Maya in Central America. There are some areas where the question as to whether writing was adopted or independently developed is in doubt, as at Easter Island.