It took between 150 and 250 years for some areas to recover so the dependency ratio was only impacted for a relativly short part of that.<p>Foreign wars are a more common ways for the issues your taking about as they kill workers not children or the elderly.  WWII failed to have the issues your talking about.<p>PS: We might be entering a time when economy&#x27;s are more manpower limited than resource limited, but unemployment trends in the US don&#x27;t support that assumption.