Wondering why moorland fires get started deliberately? I think the answer goes back a long way…
A lazy summer day in my local, pocket-sized Victorian park. Lolling urbanites enjoy trees in full leaf, lush grass, a gentle breeze, and the drifting smoke from dozens of instant barbecues. The packs, neatly stacked by the exit of the nearby supermarket, promise al fresco dining in the sun. Impromptu parties, coalescing via text message, unload drinks, crinkly aluminium trays, burgers and sausages — and matches. Unnaturally pink meat turns brown in fierce heat, then chars. The cloying smell of burnt petroleum solids mingles with odours of hot fat and seared protein. Next morning, scorched rectangles pock the grass. The marks insist that in the twenty first century, in a sophisticated city, people and fires still go together.
They always have. The mass-produced, one-time barbecue would have been a wonder to any of our ancestors, but they would have got it right away. We evolved on the only fire planet. Two billion years ago, ancient marine organisms pioneered photosynthesis, and made an atmosphere rich in oxygen. Their descendants built plant matter on the land, creating fuel. A few hundred million years later, early primates saw regular fires, ignited by lightning, sweep the landscape. Did they understand it? No. But they got used to it. Modern chimps in Senegal view fast-moving flames, lit to clear land at the end of the dry season, with equanimity. They predict how far a fire will go, how fast, and move out of the way in their own time.
That’s a crucial first stage on a path that smart primates, alone among all species, have explored. Details are obscured. Ancient ash doesn’t reveal how a fire began. But we can imagine what happened once fire was no longer fearful: Size up how this strange, wondrous, almost living thing behaves; Take hold of it; Preserve it. If it fails, learn to start a new one.
That move from observing fire to controlling it is what made us human. It is a key to a culture of experiment that underpins our whole course of technological development since. Release energy, generate heat, and we can transform materials. They let us work with higher temperatures, opening the way to new transformations. Then one day, the day we could construct machines that contain and direct the energy stored in fossil fuels, we entered the modern world. It all began with learning to light a fire.
Artificially maintained fires are prehistoric. Exactly how prehistoric is disputed. Pieces of baked clay found in Chesowanja, Kenya, could be remnants of unspeakably old hearths. If so, they warmed Homo erectus 1.5 million years ago. Alternatively, those fragments might have been baked by tree stumps that smouldered after a bush fire. However, a separate, South African, site examined in detail in 2012 revealed good evidence that the same species used fire 1 million years ago. It appears that our Palaeolithic forebears tended fires 800,000 years before we Homo sapiens came into our own.
A million-year history of pyrophilia reinforces the case that our very emergence was bound up with fire. The strongest claim is that cooking aided the growth of our brains. A dense mass of neurons needs a lot of energy to run its ever-twinkling circuitry. A regular primate, eating mostly raw vegetation, would need a hefty intake, and a vast gut, to power a brain like ours. Cooking makes digestion more efficient, so each meal delivers more calories. There are some issues with the timing: fossil skulls indicate that brains expanded before fire was definitely domesticated. But teeth adapted to food that needed less chewing very early in the human lineage. It’s pretty likely cooking helped us get smart.
Fire also sparked cognitive development in other ways. Proto-humans didn’t live at fixed sites. They were roamers. Keeping a flame alive needs forethought. You need more fuel before the fire goes out. Getting food, whether by hunting or gathering, went along with collecting enough wood to burn all night. Before we could start new fires, someone had to carry them from place to place, with the embers shielded from rain. And anyone can warm their bones by the fire, so it prompts keen interest in kinfolk who are too lazy to fetch wood but still benefit from the heat. Building fire into a way of living calls forth a new level of sophistication in planning, co-operation, and social sensitivity.
All speculative, if plausible. And there’s one other simple fact to suggest that fire was central to the lives of our forebears. Our closest living relatives among the primates sleep when it gets dark. Humans typically stay awake for 16 hours a day, yet retain poor night vision. Surely some source of light drove this change in sleeping habits?
Gradually, over hundreds of thousands of years, creatures much like us took control of fire. The remains of “Ötzi”, mummified in the alps 5,000 years ago, yielded a panoply of essential neolithic technology. Along with axes, knives, scrapers and arrows, he carried a container for embers, and a pouched firelighting kit — containing flints, and traces of pyrite and tinder fungus — for use if the embers died.
For “Ötzi” as for early humans in other climes, fire gave access to light, warmth, and cooked food. Life, when all went well, was cosy. The three-fold power of fire allowed some comfort in regions otherwise inhospitable. The fascination of the blaze — the flickering, dancing light, the sparks flying upward, the all-consuming flames — is inscribed in the myths of every culture. Fire sets humans apart from other creatures, and we knew it. Its daily presence in the camp, the cave, or the settlement, was a constant reminder. Even the earliest use of fire had the power to radically transform the day-to-day environment. That encouraged the innumerable experiments that followed.
An approachable fire is a reliable temptation. Put more stuff on it to see what happens. I remember a small boy squishing Lego bricks against the window of a solid fuel stove. A stringy residue of melted plastic stuck to the hot glass. Later, the same boy enjoyed making model kits, and then the oddly compulsive fun of seeing miniature cars and aeroplanes distorted as the hard polystyrene softened when it came near a match or, better, a small bonfire.
My stone-age predecessor would have seen flints, painstakingly shaped into axes or scrapers, used to prepare food for cooking. Heating the flint stone and allowing it to cool makes it easier to knock off the flakes that fall away to leave a useable blade — and modern humans were doing that 70,000 years ago. Another tool, a wooden spear, came from sharpening the ends of tree branches. Poking the branch into the fire helps harden the wood. It makes it more brittle, too, but at least fire speeds up the laborious scraping to get a point on the spear.
Flint knapping goes back perhaps 1.5 million years. Wooden spears have been found that are 400,000 years old. Maybe the heat-treated refinement of both kinds of tool was first discovered by accident, as early artisans worked near the fire. But something more like experiment eventually took hold. Technology gains in reach through combination. A wooden handle with a flint fastened to one end might make a javelin. It has a better blade and you can throw it instead of spear-thrusting at close quarters — faster and safer. But try jamming the flint into a notch in the wood, but it won’t be very secure in action. Tying a blade on to a branch is awkward, because a blade sharp enough to penetrate animal hide will also cut twine. The workable solution to joining things that are separate was a strong adhesive.
Sticky stuff was around — plant gum or resin can do the job. But it does not come quite ready to use. It too needs help from fire, to dry it out so it doesn’t drip off the spear before it sets. And the developed technique had another clever step. Mixing the gum with ochre makes it easier to work with. Contemporary experiments show you can fashion a spear this way, drying it carefully near a fire, in a few hours. Without heat, this kind of glue takes five or six days to harden. That’s a long time for early technologists to leave a tool alone. But snatch it up too soon, and the spear point will still dislodge easily at the crucial moment.
All this was learnt ages before policies for innovation, tax breaks for entrepreneurs, or technology supplements in newspapers. It’s hard to imagine how a usable weapon came together without serious, but also playful, experimentation. Someone — a succession of people — made time to mess around with combinations of wood, bone, stone, gum, and mineral powder. Fire was there every day. Seeing how it helped things along was always worth a try. The result, after who knows how many failures, was a superior spear, better hunting. And an enlarged sense of how the stuff of this world behaves, and how it can be changed with fire.
Fire became central to human life on planet Earth. It altered landscapes — clearing vegetation, especially forests, and altering local ecosystems, then helping prepare land for crops. It afforded domestic comfort. But above all, fire the transformer opened up a new material world. As W. G. Sebald described the twofold development. “Our spread over the earth was fuelled by reducing the higher species of vegetation to charcoal, by incessantly burning whatever would burn.” And more: “Combustion is the hidden principle behind every artefact we create.”
And here lies a contrary principle. The more we used fire, the less visible it became. Confinement was all. Clay can be shaped and dried in the sun. Put it into the fire and it hardens faster. If the fire is hot enough, it alters the clay’s structure and you can bake a vessel that is waterproof. Now a fire has a new purpose, and firing clay shifts over time from bonfire, to fire pit, to kiln.
With the kiln came enclosure. Kilns were made first to fire pottery, and to make quicklime — and hence plaster — by roasting limestone. Both call for higher temperatures than are usually reached in a bonfire or on the hearth. A closed fire chamber, and control over fuel and air supply, stokes up the heat. Maybe that began in ovens, evolved from hearths to bake grain. Either way, it allowed new experiments with fire. And turning up the heat, long before temperature scales or thermometers, opened up transformation of other materials. Smelting copper — the first usable metal because some is found in its native state — needs a reliable way of reaching 1100 degrees C. Eventually, fuel could be burned fast enough to raise the heat to the 1400 degrees C needed to smelt iron.
In time, whole cultures of manufacture and decoration, and rich technological traditions, rested on a fiery base. Firing, baking, glazing, roasting, annealing, brazing, sintering, welding, soldering — all took off from burning. The human-made world is filled with objects whose existence depends on command of heat. And the materials fire transformed made it easier to work with flame in new ways.
To begin with, fire was confined by baked brick. Hearth and oven were joined by kiln, furnace and crucible. But iron and steel fire chambers could be engineered in new ways. And that ushered in new uses of fire, and new fuels. Steam engines, with welded boilers that could (usually, fingers crossed) stand high pressure, offered static, then mobile power. The internal combustion engine dispensed with steam and applied the energy from burning directly to the moving parts of the machine. The burning now depended on ancient stored fuels, the products of photosynthesis on a fire planet hundreds of millions of years ago.
So fire, and pyrotechnology, continued to feed on itself. Wood or charcoal burning fuelled early metal production. The tools produced allowed easier felling of trees to keep the fires alight, but early metal cultures were often curbed by deforestation. Coal burning avoided that limitation. And more inventive exploitation of fossil fuels meant that metals produced in fire once again beget more fire — in steamships, locomotives, trucks, cars, planes.
The phenomenon at the heart of this is still the same. Bring fuel, heat and oxygen together and they ignite. The simplest, visible, use of this endures. Three billion people still use solid fuel — wood or dung — for cooking. But the confinement of fossil fuel combustion is the pyrological signature of modernity. It is the biggest shift in the long history of fire technology since the first cooked meal. Fire is ubiquitous as never before, but also more effectively hidden.
I am still confronted with fire directly when I strike a match to ignite my gas cooker. The gas boiler that lights each time I take a shower or tweak my heating thermostat is tucked away in the basement. If I travel by car or bus, thousands of separate ignitions each minute combine to move me along the road. There are trillions of such small, confined fires each day in the planetary fleet of well over a billion road vehicles. And the electricity I rely on for domestic comfort in a host of small ways is most often derived from the combustion driving a turbine many miles away. Today’s fires are essential but invisible. We are dependent on fire, morning, noon and night. But we forget.
Losing sight of the power of our own pyrophilia went along with blindness to its consequences. Invisible fires have an invisible product — carbon dioxide. And our construction of a global, fossil-fuel based energy system has elevated atmospheric levels of this most important greenhouse gas to heights not seen for 800,000 years.
Want to change that? Decarbonising the economy means, ultimately, dismantling all those fossil-fuelled fire technologies. Yes, that will be disruptive, and the investment needed is colossal. But we can, in principle, enjoy all the amenites that control over conflagration has allowed us to get used to without the fiery chemistry that ushered them in. Shelves of weighty studies show how we might substitute other kinds of energy capture and conversion. Maybe we can even manage it in time to avoid the worst that an altered climate can do.
But we have to really want to. And I wonder. We have loved fire for so long. Can we give it up? All those barbecues are one sign we still fetishise fire. There are plenty more. Giant, fiery explosions punctuate cinematic blockbusters. And we seek out real fires large and small. Track the world’s New Year celebrations on TV as they cross the timelines and see a global competition for the most flamboyant firework display. At the other end of the scale Wales, in 2015, saw over two and half thousand grass fires started deliberately in one small country. Arson is one of the biggest causes of fires in the UK. Insurance fraud, revenge, and the perpetrator’s thrill of watching all the fuss from the crowd account for much of it. But don’t underestimate the urge to just see stuff burn.
That urge takes many forms. If you are in a Top Gear mood, Jaguar cars still have a lot going for them. They have been in the internal combusion business a long time. The original outfit was founded a little less than a century ago to make motorcycle sidecars. After long success with classic cars, it fell on hard times, was bought, then sold, by Ford, and the combined Jaguar-Land Rover company is now owned by Tata Motors of India. The V8 engine that powers the majority of their new vehicles today is a beautifully engineered thing. If you don’t own one, there are a score of videos on YouTube of the car starting up, all accompanied by enthusiastic comments about the “brutal” sound from the exhaust.
The parts of the supercharged engine move quite fast — up to around 6,000 revs. That’s a count of the rotations of the crankshaft, going round 6,000 times a minute, or 100 times a second. A standard petrol engine, the V8 has a four-stroke cycle. Each piston goes up and down twice for each turn of the crank, with just one power stroke. Eight cylinders at 6,000 revs deliver 24,000 power strokes a minute. So the smooth ride enjoyed by the Jaguar driver begins with 400 controlled explosions every second, each triggered by a spark igniting a charge of petrol and air. The car is starting an enormously long chain of small fires.
As ever, small fires beget larger ones. The Jaguar engine can impel a car. Recently, it has found another use. It powers a fuel pump that will deliver 800 litres of hydrogen peroxide to a rocket engine. That’s a potent chemical that, run over a silver catalyst, generates hot (600 degrees C) gas — a mixture of steam and oxygen. The superheated mixture passes into a combustion chamber, where the oxygen reacts with a hydrocarbon — polybutadiene since you ask — at 3,000 degrees. All to power a vehicle that embodies ambitions beyond the dreams of Jaguar owners.
The vehicle, the UK-designed and built Bloodhound, is also called a car, though it is really a hybrid of aerospace and F1 engineering. It has a jet engine from a fighter plane as well rocket power. The jet should get it up to 650 mph. The extra thrust, initially with a single rocket, will take it to 800 mph. The designers envisage a final assembly of three rockets, which will boost the whole ensemble up to 135,000 horsepower. That will hit the final target. Behold, the 1,000 mph car!
The idea has a certain appeal. Speed records amazed through the twentieth century, but nothing much has happened since 1997, when a land vehicle broke the sound barrier. Thrust SSC still holds the record, at 763 mph. The new target doesn’t involve anything as spectacular as breaking the sound barrier but, well, it’s a round number.
When the fully-rigged vehicle runs, it will be pretty spectacular. A fighter engine and rocket power fit for a satellite launcher will both the roaring away, on the ground. The first low-speed trials, a jet-powered shakedown at a mere 200 mph down in Newquay last year drew 10,000 people.
Among them were schoolchildren from across Devon and Cornwall. The Bloodhound project is privately financed, and in continual fund-raising mode. The website offers Bloodhound SSC branded clothing, and a chance to have your name on the tailfin in tiny writing (£15 a go). The main pitch, though, is that this strange, fire-propelled vehicle, will inspire a new generation to train as scientists and engineers, and build the next generation of technologies fit for the twenty-first century.
Ironic, one may feel, that this supposedly future-oriented project is largely a demonstration of a penchant for collecting together every class of internal combustion engine and harnessing them together, one on top of the other, to power one completely impractical conveyance over a measured mile. It seems unlikely, on the face of it, that youngsters gripped by the spectacle of this automotive apotheosis, will become the designers of the technologies we actually need now — better solar panels, cheaper batteries, more efficient wind turbines.
None of those, alas, have the light-the-blue-touchpaper-and-stand-back appeal of the Bloodhound. As a concerned citizen committed to decarbonising the economy, I find that regrettable. And yet. Imagine the real trials getting under way, in South Africa some time in 2019. I can resist the offer to fly out and join the team for the next step up in speed — a projected 500mph. A few years after that, though, this wonder of controlled combustion, the most powerful land vehicle ever built, will flash across the sand at 1,000 miles per hour. As a concerned citizen, etc…. I’d really like to be on hand to see and hear that happen. Folly, of a kind, but a magnificent folly. A part of me I doubt I’ll ever lose hopes they do it, and then fire up a barbecue to celebrate.