MICROBIOLOGY
But what if, generations after the Fall, society has regressed so much that the vital knowledge of germ theory has been lost, and pestilence is once again attributed to bad air (mal aria) or fractious gods? How could a post-apocalyptic civilization rediscover the existence of unimaginably tiny creatures invisible to the eye that cause food spoilage, festering wounds, putrefaction of corpses, and infectious diseases?
In fact, bacteria and other single-celled parasites can be seen with some beguilingly simple equipment. A rudimentary microscope is surprisingly easy to make from scratch. You’ll need to start with some good-quality, clear glass. Heat the glass and draw it out into a thin strand, and then melt the tip of this in a hot flame so that it drips. The globule cools as it falls, and with luck you’ll produce some very tiny glass beads, perfectly spherical in shape. Use a thin strip of metal or cardboard with a hole in the middle to mount your spherical lens, and hold it over a sample. This simple microscope works because the tiny ball of glass has a very tight spherical curvature and thus a powerful focusing effect on light waves passing through it. This also means that the focal length is exceedingly short, though, and you will need to position the lens and your eyeball right down close to the target.*
The realization born of your instrument-enhanced senses is that there’s a whole teeming universe of invisibly small organisms down there—astonishingly diverse varieties of new wildlife for post-apocalyptic micro-naturalists to identify and sort into related families and groups. With the rigor demanded of scientific proof, you can demonstrate not only that microbes are present in infected wounds or spoiled milk, but that food is preserved if microbes are not present. If you seal nutritious broth or corruptible meat within an airtight jar and heat it to inactivate any microbes already present, no decomposition will occur: things don’t spoil spontaneously. Better microscopes can be constructed, similar to a telescope, from combinations of lenses, and in time you’ll be able link the presence of specific microorganisms to particular infectious diseases.*
You can even grow and study these microorganisms in captivity, culturing them in flasks of liquid broth or as colonies on the surface of a solid nutrient. Petri dishes can be molded from glass, filled with nutrient-enriched agar poured in to set, and fitted with a lid to prevent contamination. Agar is a gel-forming substance extracted from boiled red algae or seaweed (and common in Asian cuisine), similar to the gelatin derived from cattle bones but indigestible by most microbes.
In earlier chapters we have seen that this fundamental microbiology is needed for the optimization of processes such as making leavened bread, brewing beer, preserving food, and producing acetone. But perhaps most important in improving the human condition after the Fall, microbiology provides the prerequisite knowledge base for discovering more targeted methods than noxious antiseptic chemicals for killing bacteria and curing infection.
In 1928 Alexander Fleming had been working on cultures of Staphylococcus aureus bacteria from skin abscesses before leaving for a holiday. On his return he started clearing his lab bench and washing up the old Petri dishes. Randomly picking up one from the top of a pile in the sink that had not yet been treated with disinfectant, he noticed a small patch of mold surrounded by a ring clear of bacteria on an otherwise overgrown plate. It seemed that some substance secreted by the mold, later identified as a species of Penicillium, had inhibited bacterial growth. Penicillin, the secreted compound, and numerous other antibiotics discovered or synthesized since, are extremely effective at treating microbial infections and save millions of lives every year.
“The most exciting phrase to hear in science, the one that heralds new discoveries,” said science fiction author Isaac Asimov, “is not ‘Eureka!’ [“I found it!”], but ‘That’s funny . . .’” This is certainly true of Fleming’s chance finding, along with many other serendipitous discoveries, but only if the implications are grasped. Indeed, fifty years earlier other microbiologists had noticed that Penicillium prevented bacterial growth, but had not made the next conceptual leap from this observation to pursuing the ramifications for medicine.
With hindsight, however, and knowing of the existence of such effects, could a rebooting society replicate a similar series of experiments to deliberately search for effective molds and so rapidly rediscover antibiotics? The basic microbiology is straightforward. Fill Petri dishes with a beef-extract nutrient bed that is hard-set by seaweed-derived agar, smear across Staphylococcus bacteria picked out of your nose, and expose different agar plates to as many sources of fungal spores as you can, such as air filters, soil samples, or decaying fruits and vegetables. After a week or two, look carefully for molds that have inhibited the growth of bacteria around them (or indeed other bacterial colonies that do so: many antibiotics are produced by bacteria locked in an evolutionary arms race with one another). Pick them off to isolate the strain and attempt to grow it in liquid broth to make the secreted antibiotic more accessible. Antibiotic screens have now found numerous compounds from fungi and bacteria, although Penicillium molds are so common in the environment they are likely to be among the first re-isolated after the apocalypse. They’re one of the principal causes of spoiling food: in fact, the Penicillium strain responsible for most of the penicillin antibiotic produced worldwide today was isolated from a moldy cantaloupe in a market in Illinois.
However, even for a rough-and-ready post-apocalyptic therapy you can’t simply inject the antibiotic-containing “mold juice” because, without refining, its impurities will trigger anaphylactic shock in the patient. The chemistry worked out by Howard Florey’s research group at the end of the 1930s to purify penicillin from the growth medium exploits the fact that the antibiotic molecule is more soluble in organic solvents than in water. Strain the growth culture to remove bits of mold and detritus, add a little acid to this filtrate, and then mix and shake with ether (we saw earlier in this chapter how to make this versatile solvent). Much of the penicillin will pass from the watery growth fluid into the ether, which you need to let separate and rise to the top. Drain off the bottom watery layer, and then shake the ether with some alkaline water to entice the antibiotic compound to pass back into the aqueous solution, now cleansed of much of the crud in the growth fluid. The daily dose of penicillin for a single person prescribed today requires up to 2,000 liters of mold juice to be processed, and so post-apocalyptic antibiotics will demand a high level of organized effort to produce. By the end of 1941 Florey’s team had scaled up production to make enough penicillin for clinical trials, but they were forced by wartime shortages of equipment to improvise. Mold cultures were grown in racks of shallow bedpans and makeshift extraction equipment built using an old bathtub, trash cans, milk churns, scavenged copper piping, and doorbells, all secured in a frame made from an oak bookcase discarded by the university library—inspiration, perhaps, for the scavenging and jury-rigging necessary after the apocalypse.
So while the discovery of penicillin is often portrayed as accidental and almost effortless, Fleming’s observation was only the very first step on a long road of research and development, experimentation and optimization, to extract and purify the penicillin from the “mold juice” to create a safe and reliable pharmaceutical. In the end, the United States provided the large-scale fermentation to supply enough for widespread treatment. Similarly, once it understands the necessary science, a post-apocalyptic civilization will need to reattain a certain level of sophistication before it can produce enough antibiotic for it to have an impact across the population.
CHAPTER 8
POWER TO THE PEOPLE
The white flashed back into a red ball in the southeast. They all knew what it was. It was Orlando, or McCoy Base, or both. It was the power supply for Timucuan County. Thus the lights went out, and in that moment civilization in Fort Repose retreated a hundred years. So ended The Day.
PAT FRANK, Alas, Babylon (1959)
FLICKING BACK THROUGH the gas and elect
ricity bills for my apartment in north London, my total energy consumption last year was a little under 14,000 kilowatt-hours (kWh). If, without access to fossil fuels, all of this energy were to be provided by maintained forestry, I’d need to burn almost 3 tons of dried wood (or 1.7 tons of more-condensed charcoal) every year, which would require more than half an acre of short-rotation coppiced woodland. But that’s assuming that it’s possible to successfully convert 100 percent of the energy locked up in a log into electricity flowing from my outlets. In fact, the multistep process of combusting fuel to generate electricity is inherently inefficient, and even modern power stations can convert around only 30–50 percent of the stored energy of their fuel into electricity.
And of course, that’s only counting the energy I use directly within my four walls, for heating, lighting, and running appliances. It misses all of that expended to support my share of the industrialized civilization I live in—the energy used in road building and construction, the industrial processes needed to provide me with writing paper and powdered detergent, the energy required to manufacture and transport my clothes or sofa, and to synthesize fertilizer and plow fields for my meals, and the fuel burned by the train I take to work. When you divide national energy consumption by total population, you find that each individual living in the United States actually uses nearly 90,000 kWh every year, while a European uses just over 40,000 kWh.
Before the mechanical revolution in the Middle Ages that began the widespread use of waterwheels and windmills, and later, industrialization based on the exploitation of fossil fuels, the effort needed for agriculture, manufacture, and transportation was provided by muscle power alone. If we put this modern energy consumption into perspective, 90,000 kWh is equivalent to every American having a team of fourteen horses, or more than a hundred humans, working flat-out, 24/7 for them.
With the fall of industrialized civilization and the disintegration of this energy feed, the recovering post-apocalyptic society will have to relearn how to provide for its energy requirements. The advance of civilization is based on being able to marshal greater and greater energy resources, and especially on learning how to convert between energy types, gaining the capability to transform heat into mechanical power, for example.
MECHANICAL POWER
Civilization requires not just thermal energy, as we saw in Chapter 5, but also the harnessing of mechanical power, relieving it from the constraints of using muscle power alone.
OVERSHOT WATERWHEEL. THE RIGHT-ANGLE GEAR CONVERTS THE VERTICAL MOTION INTO HORIZONTAL ROTATION SUITABLE FOR DRIVING MILLSTONES TO GRIND FLOUR.
One of the key Roman innovations was the development of the vertical, geared waterwheel: the bottom of a large wheel with paddles is dipped into a stream or river and turned by the force of the flow. In antiquity, this water power was primarily applied to turning a grinding stone to mill flour, and the crucial mechanism that allowed this technology was the invention of the right-angle gear (dated to around 270 BC), transforming the direction of motion from the vertical spin of the waterwheel to the horizontal rotation of the grinding stone. Most simply, this can be achieved with a large crown wheel (one with pegs sticking out of the flat face of the gear) on the waterwheel drive shaft, coupled to a cylinder of rods known as a lantern gear or cage gear that is connected to the millstone. Altering the relative sizes of the crown wheel and lantern gear allows you to match the required speed for grinding to the flow rate of different rivers. These water mills were the very first known application of gearing to transfer power, and so represent the earliest roots of mechanization.
Although it can be dunked in the flow from practically any riverbank, or even mounted over the side of a milling boat anchored in the current, the undershot wheel is woefully inefficient, and in its simplest form suffers from problems with varying river levels. Luckily it doesn’t take much technical know-how to build a far more capable and powerful waterwheel. The overshot wheel became widely exploited across Europe during the supposedly ignorant and stagnant “Dark Ages” following the fall of the Roman Empire, and, despite similarities in overall appearance, functions on a completely different principle than the primitive undershot wheel.
Rather than being stuck into the flow, the bottom of the overshot wheel is held clear of the tailrace, and water is delivered to the very top of the wheel by a chute. The overshot wheel derives its torque not from the impact of a current, but from the energy relinquished by the water as it falls. This design is far more efficient and can capture as much as three-quarters of the energy held in the head of water. Fit a sluice gate to the chute to control the flow onto the wheel, and if the stream is dammed to create a mill pond, a reservoir of energy can be built up until it is required to be expended (something that wasn’t attempted until the sixth century AD, half a millennium after the first vertical waterwheels were used, but could be leapfrogged to during a reboot).
SELF-ORIENTING TURRET WINDMILL. THE FANTAIL KEEPS THE MAIN SAILS TURNED INTO THE WIND, AND THE CENTRAL SHAFT DRIVES TWO SETS OF MILLSTONES.
Harnessing wind is technically much trickier than tapping into water power, and consequently the technology arrived much later in our history of development (although boats with sails to catch the wind for propulsion date back to 3000 BC). Water is a far denser medium than air, and so even a gentle flow carries a great deal of energy, making it an easy resource to exploit even with imperfectly designed elements and inefficient wooden gearing. Unlike the sluice gate, you have no control over the strength of the wind, so if it begins blowing too briskly, the windmill blades or driven mechanisms can be damaged. Windmills therefore need a braking system and a method to control the effectiveness of the blades, such as reefing canvas sails. The most fundamental challenge, however, is the constantly changing wind direction; a windmill needs to be able to be quickly reoriented.
Rudimentary windmills can be built on a post and the entire structure manually turned to the wind, but for larger and more powerful fixed windmills the blades need to be mounted on a top turret able to automatically swivel around the central drive shaft to face into the wind. The mechanism employed here is ingeniously simple: a small fan behind, and facing at a right angle to, the main sails is geared to a toothed track running around the top rim of the tower, so that whenever the wind changes and blows across this fantail, it spins and rotates the turret around until it is oriented perfectly in line with the wind again.*
All of this demands a much greater degree of mechanical sophistication than even the largest waterwheel. But once you’ve mastered wind power, your sites of production are liberated from the watercourses and can occupy even flat landscapes (like the Netherlands), or regions either without abundant water resources (such as Spain), or that are often frozen over (like Scandinavia).
FUNDAMENTAL MECHANISMS: THE CRANK (RIGHT) TRANSFORMS ROTATION INTO A BACK-AND-FORTH MOTION SUITABLE FOR SAWING, AND THE CAM (LEFT) CAN BE USED TO REPEATEDLY LIFT AND DROP A TRIP-HAMMER.
The taming of the wild power of both wind and water, coupled with the increasingly effective use of draft animals (we’ll return to this later), had a profound impact on our society, and you’ll want to achieve the same level as rapidly as possible during the reboot. Medieval Europe became the first civilization in human history to base its productivity not on human muscle power—the labors of coolies or slaves—but on the exploitation of natural power sources. This mechanical revolution, gathering momentum between the eleventh and thirteenth centuries, went far beyond the use of a mill to pulverize the harvest’s grain into flour. The potent torque of the waterwheel and the windmill became a ubiquitous power source for a staggeringly diverse range of applications: pressing olives, linseed, or rapeseed for oil; driving wood-boring drills; polishing glass; spinning silk or cotton; powering metal rollers to squash iron bars into shape. The elementary mechanical component that is the crank arm transformed rotary motion into a reciprocating thrust suitable for mechanizing sawmills, venti
lating mine shafts, or pumping water from mines or flooded lowlands (as employed to great effect by the Dutch). But perhaps the most versatile function was turning a cam to repeatedly lift and drop a trip-hammer—perfect for crushing metal ore, pounding out wrought iron, crumbling limestone for agricultural lime or mortar, beating dirty sheep wool to full it (to clean and compact it), and pounding mash for beer, pulp for paper, bark for tanning, and woad leaves for blue dye.
The cam mechanism was employed to heave trip-hammers for seven centuries before being replaced by steam-powered versions in the Industrial Revolution, but it lives on today under the hoods of our cars and trucks, opening and closing the engine valves in the correct sequence (see Chapter 9).
The Knowledge: How to Rebuild Our World From Scratch Page 16