Key Asp Upload What Has Been The Key To Bare Societal Subsistence Throughout History To The Present Day?

What has been the key to bare societal subsistence throughout history to the present day? - key asp upload

Some definitions of "maintenance" for those who do not know what that means ...

http://www.mw.com/dictionary/subsistenc ...
http://dictionary.cambridge.org/define.a ...
http://encarta.msn.com/dictionary_/subsi ...

This is not a task. I want to see what people have ideas ...