I never intended to imply that we should go back to the Paleolithic. It has been made impossible by the population boom, which was spurred by agriculture. The thing is, agriculture actually decreases food security. If you depend solely on a handful of crops, which can only be harvested once a year, blight, drought, or any of a dozen natural disasters can destroy your entire food supply. Further, agricultural societies suffer from dietary deficiencies in many proteins and vitamins, and get many diseases from their domestic animals (smallpox, influenze, plague from rats eating stored grain, etc.). If it were at all possible, a return to hunter-gatherer societies would still improve the average living conditions.

Since it is not a viable option, there are only a few ways in which we can deal with Malthusian economics. First, we can attempt to limit population growth. Unfortunately, unless everyone can agree to produce only 2.1 children per couple, some people will need to be coerced, which is ethically very shaky. Second, we can increase our ability to utilize existing renewable resources. The improved solar converters mentioned above would help, as would intensified use of the oceans and lakes as centers for food production. Fish farms date back to the heyday of the Hawaiian empire, and work surprisingly well for the manpower requirements. Such measures will only work for a limited period of time, unless world birth rates fall in line with those of the industrialized world. Finally, there's looking for somewhere else to live. We've emigrated whenever population pressures got too much, and it's not as if the subject hasn't been given any thought. The only problem is finding another habitable planet we can reach.