Al Stahler: A short history of fire
Life has lived on Earth for close to four billion years. Over that time, conditions have changed many times … often drastically.
The earliest life lived on an Earth with no oxygen in the air, nor dissolved in the water (which is what fish breathe today) … and it did fine.
Life on Earth has endured ice ages … the most recent ended just ten thousand years ago. Twenty thousand years ago, glaciers flowed over I-80, down SR 20, into Bear Valley. Farther back, our planet has frozen over completely … and life survived.
Earth has also been a hothouse – the dinosaurs enjoyed the warmth, as did our ancestors, early mammals. Hothouse Earth critters lived year-round in the Arctic.
Then Earth switched back into Icehouse mode, and the Arctic froze over. Through all this, life thrived.
To survive on an ever-changing planet, life has two basic strategies. One strategy: Evolve.
When a rock the size of a mountain slammed into Earth, sixty-six million years ago, the dinosaurs were done for. But one group of dinosaurs survived … and evolved into the birds that fly through our skies today.
But evolution takes time: Many generations, many years. Humanity is no doubt evolving … but we cannot wait so long, to deal with Earth changes today.
For much of Earth history, fire did not exist. In life’s earliest days, there was no oxygen in the air. No oxygen, no fire.
Then blue-green algae – cyanobacteria – evolved. The blue-greens did not invent photosynthesis – making food with the energy of light – but they did invent a form of photosynthesis that involved busting up water molecules: Pulling hydrogen atoms away from oxygen atoms, using those hydrogens to make food. The oxygen atoms were useless … worse, they were toxic … and the bacteria threw them away. Once the water could dissolve no more, the oxygen bubbled into the air.
Still, all life lived in water, nothing on land. Life was wet; there was nothing dry enough to feed a fire.
When plants finally crawled out of the water, onto the land, they could barely stand up. The cellulose that gave shape to their cells was too squishy – it could shape a plant in the water, but could not stand up to gravity on land.
It was only when plants evolved a new chemical to mix with cellulose – lignin – that they could invent wood. Maintaining their shape with wood, cells were strong enough to build trees.
Cellulose, on its own, was not only too weak to stand up against gravity; it was also easy to digest, making easy pickin’s for microbial and fungal digestive enzymes. When a plant died, it was quickly devoured.
Lignin, though, made wood hard to digest. If, today, you find a downed tree, rotting in the woods, you can often find within it squarish brown blocks, an inch or two on a side – this “cuboidal rot” is composed mostly of lignin, the wood’s cellulose having been digested away.
With lignin making wood harder to digest, dead wood could remain on the ground longer … and fuel could build up. Fire could now spread across the landscape.
Fireweed is a plant – a wildflower – one of the first plants to grow back after a fire. It is one of many plants that have evolved to deal with fire. But – as noted above – evolution takes time.
A second, faster way of dealing with change: Adapt.
Adaptation can take many forms. We can pick up and go elsewhere: Migrate.
But I like living in the foothills … I like the fact that a trip to the grocery can take twice the time it should … because I might run into a neighbor I haven’t seen in ages, and we chat. I don’t want to leave.
If I – we – are staying put … how might we adapt?
Drought and flood, wind and lightning have been part of life in California for longer than humans have lived on Earth. Fire has long been part of life in California.
When the first Californians arrived, some tens of thousands of years ago, they learned to live with flood, and with fire.
Since then, mistakes have been made. We’ve allowed fuels to build up. What now?
Very few super-complicated problems have one, simple answer.
When we pick up a rock, let it go, and it falls to the ground … we think of the rock “wanting” to fall downward. But rocks don’t have brains … they simply follow the laws of the universe. We harness those laws when we use falling water to generate electricity.
Right from the start, life has harnessed the laws of the universe, to keep itself alive. The food we eat, if allowed to dry out … and given a spark … would combine with oxygen, and burn. We harness the fact that food “wants” to burn – “wants” to combine with oxygen – by allowing food to combine, slowly, with oxygen … releasing energy … keeping us alive.
We can fight – or ignore – the laws of the universe, but for only so long. If are to survive in the universe – if we are to be safe with fire – we must learn to live with it.
There are no simple answers.
Al Stahler enjoys sharing science and nature with friends and neighbors in The Union and on KVMR-FM. He teaches classes for both kids and grown-ups, and can be reached at firstname.lastname@example.org
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