What is civilization?

I had wondered from time to time how it was that writing was not invented in the New World ; the only answer I had come up with was that somehow the need for writing had never arisen -- that may be true, of course, from the Old World point of view; we Old Worlders tend to think that "necessity is the mother of invention." but this is not necessarily true, and also writing seems to be something more than just an invention -- great works of literature, for example, seem to be much more than, or have much more reality than, just a collection of various alphabetical symbols formed and arranged according to rules invented by a group of inventors, as works of art have a reality external to their material , and so on. But to get down to the main point : the problem with the question may be that it is based on wrong presuppositions about what civilization is and how it comes into being and how it grows; it may be that the invention of writing is not a necessary part of the growth of a civilization. More importantly, the main points and last! , current Old World civilization's history is a very small fraction of the period of the homo sapiens' life on earth. But since we only happen to know the historical part of that period in any real detail, we tend to overemphasize the events of the historical period. And if someone objects that real culture and real human existence begins with settled city life -- we will not quarrel with him, since so far the above is simply an arbitrary or semi-arbitrary definition. But if he goes on to say that civilization in the sense of city life necessarily leads to the invention of writing, he would be contradicting the evidence of New world civilizations -- and no one could reasonably deny that the great Aztec, Inca, and Maya societies and so on were in any way anything less than civilizations.