The Knowledge: How to Rebuild Our World From Scratch Read Online Free PDF

Omega man or woman dies—the situation in Richard Matheson’s novel
I Am Legend
. Two survivors—a male and a female—is the mathematical minimum for continuation of the species, but the genetic diversity and long-term viability of a population growing from just two individuals would be seriously compromised.
    So what isthe theoretical minimum needed for repopulation? Analysis of the mitochondrial DNA sequences in the Maori people living in New Zealand today has been used to estimate the number of founding pioneers who first arrived on rafts from Eastern Polynesia. The genetic diversity revealed that the effective size of this ancestral population was no more than about seventy breeding females, and so a total population a little over twice that. A similar genetic analysisdeduced a comparable founding population of the great majority of Native Americans, who are descended from ancestors who crossed the Bering land bridge from Eastern Asia 15,000 years ago when sea levels were lower. Thus a post-apocalyptic group of a few hundred men and women, all in the same place, ought to encapsulate sufficient genetic variability to repopulate the world.
    The problem is that even with a growth rate of 2 percent per annum, the fastest the world’s population has ever grown when sustained by industrialized agriculture and modern medicine, it would still take eight centuries for this ancestral group to recover to the population of the time of the Industrial Revolution. (We’ll explore in later chapters the reasons why advanced scientific and technological developments probably require a certain population size and socioeconomic structure.) And such a diminished initial population would probably be far too small to be able to actually maintain reliable cultivation, let alone more advanced production methods, and so would regress all the way back to a hunter-gatherer lifestyle, preoccupied with the struggle for subsistence. Ninety-nine percent of human existence has been spent in this lifestyle, which cannot support dense populations and represents a trap that is very hard to progress out of again. How do you avoid regressing that far?
    The surviving population would need plenty of hands to work the fields to ensure agricultural productivity, yet leave enough individuals available to work on developing other crafts and recovering technologies. For the best possible restart, you’d also want the survivors to number enough that a broad swath of skill sets is represented and sufficient collective knowledge is retained to prevent sliding backward too far. Thus an initial surviving population of around 10,000 in any one area (which for a large state such as Texas represents a survival fraction of only 0.04 percent), who are able to gather into a new community and work peacefully together, represents the ideal starting point for this thought experiment.
    So let’s turn our attention to the sort of world that the survivors will find themselves in, and how it will change around them as they rebuild.

RECOLONIZATION BY NATURE
    Immediately after the termination of routine maintenance, nature will seize its opportunity to reclaim our urban spaces. Trash and detritus will collect on the streets and pavements, blocking drains and causing the pooling of water and accumulation of debris rotting into mulch. Pioneering weeds will first begin proliferating in pockets like this. Even in the complete absence of pounding car tires, cracks in the asphalt will steadily expand into crevices. With every frost, water pooled in these depressions will freeze and expand, crumbling the hard artificial ground from within with the same punishing freeze-thaw cycle that steadily wears down entire mountain ranges. This weathering creates more and more niches for small opportunistic weeds, and then shrubs, to become established and further break up the surface. Other plants are more aggressive, their penetrating roots pushing right through the bricks and mortar to find