How has the constitution survived for more that 200 years?

Answer 1

The US Constitution has survived for 220 years because it provides for amendments to solve problems as they arise. It also provides for the basic structure of government and not a whole lot of detail. It divides the government into three separate branches. When one or two branches can not or will not solve a pressing problem then the third one can. President Harry S Truman started the Civil Rights Movement by himself. Then the courts acted. Finally congress acted. One branch of government at a time acted.
The division of powers does not work in France because of the difference in the court systems. The courts do not have defendants face accusers and do not follow precedents. A supreme court can not issue decrees binding on lower courts. The president can not act when parliament is in chaos. Instead, France goes through five republics and a few monarchies while the United States has one flexible form of government where each branch functions independent regardless of what is happening in the others.

Answer 2

Paper deteriorates because of interaction with various substances in the air such as water (the humidity level). Keeping the declaration in an air tight container already preserves it from interaction with all the air around it and it also protects the document form minor damage from the outside world. However, that won't protect it for 200 years. For it to last that long it must be kept in a specialized container that regulates the temperature as well as humidity levels inside of it. Keeping the document in low humidity, low oxygen and the right temperature (I'm not too sure what it is) ensures survival of the constitution for decades to come.