Those would be the exceptionally lucky ones.
How many people do you know today who don't even have a backyard to dig up to plant a garden, to say nothing of having no seeds or tools, nowhere to fish or hunt, don't even have jars to can with, no a clue on how to do it, to say nothing of having nothing to can?
I planted a significant garden this year for the first time in many years; next year I'll be doing a lot of things differently.
What's mind-boggling is how much space is needed to grow significant calories; 100 square feet will, on a good season, produce 30,000 calories of potatoes.
That will feed one person a starvation diet of 1000 calories per day for one month.
Scale from there.
bump
You can do a LOT more with potatoes if you go vertical.
Try this out some time. The neat part about it is you can peel away the base and start eating ‘taters while the top wrungs are still growing.
http://lifehacker.com/5202849/grow-100-lbs-of-potatoes-in-4-square-feet