Let's go back to the dusty time of the New Testament and imagine Jesus, a man who claimed to be the son of God, saying this to his followers on a hot day: "I'm captivated by the revelation that my breakfast feeds the 100 trillion bacteria and archaea in my colon, and that they feed me with short-chain fatty acids." Can you imagine that? No, you can't. For one, everyone in those raw Roman days had no idea that lots of tiny things (bacteria, protists, and viruses) existed far, far below big things (humans, donkeys, and whales). They had no idea that the cells in all large life-forms not only are descendants of prokaryotes (cells without a nucleus) but support in themselves communities of microbes. We are nothing but the art of these invisible beings.

Because it is a fun thing to do, let's put some more unexpected words into the mouth of the man who, according to a very popular book, died because human sins are somehow a really big concern for the supreme force behind the creation of the vast and ancient universe: "I'm thrilled by the fact that I am farmed by my microbes as much as I cultivate them, that bacteria modulate my physical and mental well-being, and that my microbes are programmed to eat me from the inside out as soon as my heart stops delivering oxygenated blood to my gut. My bacteria will die too, but only following a very fatty last supper." Indeed, this is the real last supper. The mostly friendly microbial community that first formed in our guts not long after we were born, and gradually became a complicated and fluctuating inner ecosystem, turns against us when we are nothing to them but dead. They eat the walls of our digestive system, our meat, and finally our skin. During this last supper, we become bloated with their foul gases.

The words I put in Jesus's mouth (certainly to the horror of those who believe in Him and believe that cleanliness is Him) came from a passage found at the bottom of the antepenultimate page of a beautifully written collection of linked essays called The Amoeba in the Room: Lives of the Microbes. The book is by Nicholas P. Money, a mycologist who teaches at Miami University (mycology is the study of fungi). Though Money is a scientist, he does have this in common with the prophet who was born in a manger 2,000 or so years ago: He wants to bring the word to humankind.

Money's word is this: Biology has been and still is dominated by zoology and botany—the biology of very big things. Why? Because humans, as with all other animals, are obsessed, are mesmerized by things that are visible to the naked eye. When we speak about the diversity of life, we have in mind images of endangered rhinos and equatorial jungles. Even the cover of the Belknap Press's 1992 edition of E.O. Wilson's much-admired The Diversity of Life has on its cover a picture that readers of Charles Darwin's On the Origin of Species will immediately recognize as a reference to the "entangled bank" passage: "Clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth." But this is a very limited and almost unhelpful view of what biology is mostly about.

Even when it comes to the sea, we still focus only on massive creatures like whales, sharks, seals, and the rest. But we completely ignore the main form of life that rules our great bodies of water—single-celled organisms. "There are... as many blue-green cells floating in the sunlit waters of earth as there are atoms organized in a human body." And yet these microbes (so fucking many of them all over the place: air, bathrooms, a teaspoon of soil)—and this is where Money purposely steps on some very sensitive anthropocentric toes—are vital to the human world, and animals like whales are just not.

We can lose all of the worlds of giant turtles and clever dolphins and not fear the end of our world—the same goes for them, with respect to us. But if, say, Prochlorococcus, an ocean-dwelling cyanobacterium, were to stop incorporating carbon into its cell, our world would be totally fucked. And here I must make a distinction between worlds and the planet. There are many worlds on this one planet we call Earth. The most resilient worlds out there are microbial.

To make people understand this deeper truth of living things, Money provides this gorgeous sermon on sushi:

To approach a meaningful picture of marine biology, we need to put aside the things studied by zoologists. A sushi bar to end all sushi bars will foster the necessary thought experiment. Every morsel of marine muscle must be eaten in this last supper: all the hagfish, lampreys, sharks, rays, and bony fish are diced, rolled in sticky rice, wrapped in seaweed, kissed with soy sauce, and swallowed; the red meat from whales, dolphins, manatees, and walruses works well as sashimi and sea turtles make soup; all the oysters slip down with the assistance of cold white wine, all the squid are crunched calamaried; orange sea urchin gonads make a sloppy topping for sushi rolls and jellyfish can be fried. Crabs and lobsters are dispatched after boiling, along with the related sea spiders, barnacles, and fish lice. This is a lot of food: fish, great whales, and Antarctic krill alone weigh more than 1,000 million tons. That leaves the sponges and comb jellies, penis worms and other worms, and exotics like mud dragons, but most of the gustatory labor is over and the ocean is much clearer for it. Now we can turn our full attention to the 90 percent of living things in the sea that cannot be seen without a microscope.

Money has a great style, and a very important message. To see what is really going on in the biosphere, the only zone of life that we know of at this point, you need a microscope. Bacteria are the gods of humans. recommended