Our alliances with microbes have repeatedly changed the course of animal evolution and transformed the world around us.
It is easier to appreciate how important these partnerships are by considering what would happen if they broke. Imagine if all microbes on the planet suddenly disappeared.
On the upside, infectious diseases would be a thing of the past, and many pest insects would be unable to eke out a living. But that’s where the good news ends.
Grazing mammals, like cows, sheep, antelope, and deep would starve since they are utterly dependent on their gut microbes to break down the thought fibres in the plants they eat.
The great herds of Africa’s grasslands would vanish. Termites are similarly dependent on the digestive series of microbes, so they would also disappear, as would larger animals that depend on them for food, or on their mounds for shelter.
Aphids, cicadas, and other sap-sucking bugs would perish without bacteria to supplement the nutrients that are missing from their diets. In the deep oceans, many worms, shellfish, and other animals rely on bacteria for all of their energy. Without microbes, they too would die, and the entire food webs of these dark, abyssal worlds would collapse. Shallower oceans would fare little better.
Corals, which depend on microscopic algae and a surprisingly diverse collection of bacteria, would become weak and vulnerable. Their mighty reefs would bleach and erode, and all the life they support would suffer.
Humans, oddly, would be fine. Unlike other animals, for whom sterility would mean a quick death, we would get by for weeks, months, even years.
Our health might eventually suffer, but we’d have more pressing concerns. Waste would rapidly build up, for microbes are lord of decay.
Along with other grazing mammals, our livestock would perish. So would our crop plants; without microbes to provide plants with nitrogen, the Earth would experience a catastrophic de-greening.
“We predict complete societal collapse only within a year or so, linked to catastrophic failure of the food supply chain,” wrote microbiologists Jack Gilbert and Josh Neufeld, after running through this thought experiment.
“Most species on Earth would become extinct, and population sizes would be reduced greatly for species that endured.”
Microbes matter. We have ignored them. We have feared and hated them. Now, it is time to appreciate them, for our grasp of our own biology is greatly impoverished if we don’t.
From the book “I Contain Multitudes” by Ed Yong. Copyright © 2016 by Ed Yong. Reprinted courtesy of Ecco, an imprint of HarperCollins Publishers.
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