Al Stahler: You can learn a lot, in four billion years
Let’s step back in time – a few million years – to when our early ancestors walked the African savannah (savannah = grassland with scattered clumps of trees – think: lower Sierra foothills). These people had long since left their chimpanzee cousins back in the trees, yet they held onto – we still enjoy – things that came in handy … fingers had been great for swinging tree-to-tree; they’re useful, still, for typing, texting and such.
Modern chimps have also evolved, to make a living on a modern Earth.
Stepping back further, a few billions of years, we find a world inhabited by single-cell bacteria, from whom we’ve also inherited useful traits: We “burn” our food for energy, just as they did.
Modern bacteria – those that make yogurt, or infect a cut – have also evolved to live on a modern Earth.
Step back further still – four billion years – and we reach a time when Earth was lifeless: Life had yet to evolve, from rocks and air and water.
We like to give human attributes to non-human things: The harsh winter wind is cruel; the hurricane takes aim on a city; the earthquake heartlessly reduces hopes and dreams to rubble.
But winds and storms and quakes have no brains, no hearts, no emotions. They simply follow the laws of physics: Gravity pulls things downward; warm air rises; when water freezes, it expands (which is why that bottle of beer you forgot in the freezer exploded).
The laws of physics also play out on the tiniest of scales. Paper burns; iron rusts; saltwater evaporates; salt crystals grow: Nature playing out on the scale of atoms.
Before anything alive populated the Earth, atoms flew around, bouncing into each other: Most bounced off, but some linked up to form clumps – molecules. Molecules could then link up to form larger clumps … or they could fall apart. Some clumps traded atoms, like kids trading baseball cards.
When a crystal grows, atoms join together, like a wall building itself out of bricks, in a pattern dictated by the bricks below.
Break a crystal in two, and the pattern remains, allowing each half to continue growing. Where once there had been one crystal, now there are two … both growing.
Imagine a time on the non-living Earth, when atoms – following the laws of physics – join to form … not crystals, exactly … but clumps with a pattern to them.
Like a crystal, these clumps would dictate how other atoms could join, to keep the pattern going … to keep the clump growing. And, again like a crystal, the clump might break in two; each half would re-grow, keeping the pattern going … and keeping the clumps – now two of them – growing.
If the two should both break, there would then be four.
These clumps of atoms are following basic laws of physics … they are NOT alive. But they are replicating – they are reproducing themselves. Replication is a useful – ESSENTIAL – skill for a living cell … a skill our own cells have inherited, from non-living replicators.
The descendants of the replicators have themselves made it, through four billion years, to the present. And they, too, have evolved … not to “make a living” – they’re still not alive – but they’ve evolved to continue replicating in the modern world.
These replicators are viruses.
In the mid-twentieth century, an idea floated about, that our brand-new wonder drugs, might, someday soon, put an end to infectious disease.
But four billion years is a long stretch of time – time enough for bugs – even non-living replicators – to hide quite a few tricks up their sleeves.
Ecology is the study of how living things live together … how they share food, water, air, living space. One of the wonders of ecology is that it all works out so smoothly … all the gears mesh … most of the time. Sometimes things don’t mesh real well.
One of the biggest problems for an infectious organism – virus, bacterium, gut worm – one of their biggest problems is finding a new host to infect … getting out of one body, into another.
Throughout our history, humans have never been a common animal. At times, in fact, human populations have dropped so low, we were an endangered species.
But, just in the past few thousand years, that has changed. Humans now outnumber all other large mammals.
Add, to huge populations, ease-of-travel – from one side of the world to the other in half-a-day – and we’ve solved the bugs’ biggest problem for them. Suddenly, they’ve got lots of potential victims.
Just as species evolve, so do ecosystems – the ecological systems in which we live. It will be interesting – to say the least – to see how human ecosystems evolve over the coming months and years.
We’re not helpless. Just as replicators have been evolving for four billion years, so have immune systems. Half-a-billion years ago, animals made an evolutionary leap in immunity. At the same time, we evolved sleep, and muscles. Likely because they co-evolved, our immune systems now depend on sleep, and movement.
The moon becomes full, just after midnight, Wednesday night/ Thursday morning. The moon is full when it is exactly opposite the sun in the sky, so the full moon rises, in the east, right around sunset, in the west.
Al Stahler enjoys sharing science and nature with friends and neighbors on KVMR-FM, and can be reached at firstname.lastname@example.org.
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