Humans are completely out-matched by viruses—yet viruses also provide us with essential services
PANDEMICS, LIKE BIRTH AND DEATH, have always been with human populations. History is composed of pandemic layered upon pandemic as far back as written records extend.
The plague of Antonine, almost certainly the smallpox virus from the description of its symptoms by the Greek doctor Galen, rode home with troops returning from a Middle Eastern war, swept through the Roman Empire, and killed an estimated one in 10 of its 75 million citizens.
Victims included the Roman emperor Lucius Verus, co-ruler with Marcus Aurelius, who is perhaps better known for the Stoic philosophy that must have kept him going while plague was killing 2,000 people a day in Rome. The current daily death total in the US during the COVID-19 pandemic is now 2,000-a-day and projected to rise to 3,000 a day by June. The more things change, the more they get the same.
Later, in 735 Japan, the smallpox virus killed about one-third of its population over the course of two years.
When smallpox arrived here on the West Coast for the first time in 1782, travelling its perambulatory path from an outbreak in Mexico, it killed every second person, a mortality rate about double that which had afflicted ancient Rome and early medieval Japan.
Viruses leap from animal to human populations when they find fertile ground and then they leap from concentration of humans to concentration of humans until they’ve either killed off enough hosts that they reduce their transmission options, or their hosts adapt their immunity, or the viruses adapt to their hosts so that they can live in a symbiotic, sometimes mutually beneficial relationship.
It doesn’t make evolutionary sense to kill off the host that keeps you alive; viruses that do soon disappear along with their dwindling transmission possibilities.
And so it does make sense that some viruses which reside in the mucus that lubricates human respiratory, digestive and reproductive tracts, for example, protect the medium in which they live—and thus us—by killing harmful bacteria. They are helping to keep the world in which they live intact.
Our quirky, sometimes uncomfortable coexistence with microorganisms is hardly surprising considering that we live in a vast ocean of them. The math is astonishing. As part of the global biomass, humans, it’s been pointed out, amount to little more than a rounding error, about one ten-thousandths of the total. Microorganisms, by comparison, amount to 13 percent of the total. Viruses alone represent about three-and-a-half times the total biomass of 7.5 billion humans.
In fact, microorganisms comprise a big part of us from the day we’re born until the day we die and they begin to dismantle and recycle us.
For every cell in the human body, there are 10 microorganisms, most of them benign, many—including viruses—which are essential to our survival. Only a few are temporarily lethal to us until we eventually learn how to adapt to them or they to us.
The variety of coronavirus that’s disrupting global civilization for the moment—the inconvenience of social distancing may seem interminable to us but it’s a tiny fraction of our time on Earth and a minuscule fraction of a fraction of a fraction in evolutionary time—tends to be anthropomorphized as “the enemy” and demonized as though it were following some nefarious conscious imperative.
Electron microscope image of the new coronavirus SARS-COV-2
Yet, if it weren’t for viruses, we likely wouldn’t even be here to complain about them.
It turns out that viruses kill 80 percent of the bacteria that inhabit the ocean deeps. This in turn releases the nutrients upon which bacteria higher in the water column feed. Those bacteria are themselves crucial nutrients for the single cell organisms upon which the entire marine food chain rests.
At the top of that food chain are humans.
And so, even as we curse the COVID-19 virus and its hazards and inconveniences, the tuna melts we make for lunch actually come to us courtesy of its very convenient cousins.
Stephen Hume has spent half a century as a journalist writing about Western Canada, the Far North, BC and the Island.
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