I almost forgot about this thread, until I just read the latest post, by our new 'liberal' friend. So let me say something about why I posed this question in the first place.
Although I am not a 'Cultural Anthropologist', but rather a 'Physical Anthropologist', I have had a good deal of training in Ethnology and archaelology. And during one of my courses in S.W. Archaeology, a female student was answering a question posed by the classes' professor. And toward the end of this, she made the comment that "And since Necessity is the Mother of Invention", she was suddenly halted in mid-stride.
The prof told her to hold up because she was totally confused. The saying that "necessity if the Mother of Invention" is almost entirely incorrect. It seldom occurs, and for good reason.
And to demonstrate his point, he pointed us all to the Anasazi(Cliff Dwellers) and how they were driven out of their cliff dwellings during the 300 year drought event somewhere between 900AD and 1200AD. Somewhere toward the end of the drought, the Anasazi villages were totally abandoned, and they passed into history.
His point was that like them, and other primitive cultures, when events threaten a society, the first thing they always fall back on is what helped in their success. If a hunter gatherer society comes on hard times, and their food supply dramatically drops off, that society will hunker down and exploit the remaining game, until it is hunted out completely. Then and only then will that society try something else, such as migrate to a more numerous game location. Almost never will that society branch out and try something new and unproven.
Consequently, the Anasazi intensified their agricultural approach AND added to their hunting history, until the local game could no longer support them. There is absolutely no evidence of the Anasazi attempting to modify their irrigation techniques, change crops, or apply other innovation. They just continued to lose out until they finally gave up and left the area.
On the other hand, almost all innovation is achieved through accident, or as a result of something unrelated to the necessity, but applied at leisure, so to speak. This is not saying there are exceptions, but generally it just isn't so.
Necessity is almost Never the Mother of Invention. Humans are, by nature, conservative, in that they are reactionary and resist change. This is why I completely disagree with the general use of "Conservative" as a generalized political movement. Everyone is conservative by nature. Its in our genes.