Can Permaculture sustain us?

     Toby Hemenway is one of the best-known Permaculture advocates available. He is quite knowledgeable on the subject, and gives talks and teaches courses over there on the west coast. An article from his website was probably the best gardening article ever written, which is to say most horticultural information is content-milled. That article really inspired me to find out what is native and useful here, and I can't imagine living anywhere else.
     But can Permaculture really sustain us? Some people think of it as more of a religion rather than an agricultural technique, which is definitely a problem. And the answer, which Mr. Hemenway sidestepped a bit, is that it cannot. Unless we change every aspect of our lives to really coexist with the planet. That would include less future children, and not more. Less fossil fuels, not more. Less air conditioning and heating, and not more. Less can be more with proper design, hence, permaculture.
      It really comes into perspective when you attempt to figure out the acreage it would take for a family to feed itself. More than one acre, for sure. At least one adult working  full-time on that acreage to plant, harvest, and maintain production. Families would be forced to to move to be spread out in order to have that land for use. The surface area of the arable parts of the planet is known and can be calculated. The calculations do not add up to the population numbers that we have now.
     That's sad, right? Not really. I can't even tell you all the people that I've met that never want to have kids. They are a product of our industrial society, and they don't want to give up the luxury they would miss out on  if they had to raise children. Then there is also the fear that this industrial society isn't worth living in, that it would be a shame to bring a child into this. Personally I think that's why zombie flicks are so popular, because people secretly long for a less complicated life where the threats to your welfare are clearly visible. Children are an investment no matter what your ethics and religion, of time, energy, even patience.
     But that's just one aspect of how lives must be changed to have a future for our race. Toby Hemenway  forsees a potential future for us that he describes well in this video. What do you forsee?