When Walt Whitman declared “I contain multitudes,” he had no idea that it was more than just a metaphor. Ed Yong, a science staff writer for The Atlantic, provides an entertaining, fascinating, sometimes thought-provoking, sometimes kind of gross survey of the microbes that live within us as well as other animals.

The microbiome is a big deal of late. You may have heard about it. You may also have heard about Fecal Matter Transplant in which poo from a person with a healthy gut is transplanted into someone who is sick. The idea is the healthy bacteria will take hold in the sick person and bring their stomach and intestines back into working order. And it does for certain kinds of problems. In fact it works so well, you can find instructions on the internet about how to do this yourself. Not recommended, however, as Yong notes a number of DIY people have shown up at hospitals with some raging infections because of it. Yong dedicates almost an entire chapter to FMT and the scientists and doctors who are working to figure out which microbes are the ones we really need, grow them in a lab and create an easy to swallow capsule sans poop. Though one of the researchers who is testing out a capsule calls it “Repoopulate.” Ah those wacky scientists!

Scientists have known about the microbes in our bodies since the 1600s. At that time they could see them with a microscope but had no idea what they did. Time and science progressed and the idea of probiotics was floated out there but no one could really prove anything. Then the age of antibiotics was ushered in followed quickly by the belief that all “germs” were bad and needed to be killed. Bacteria can definitely be nasty critters, but it turns out, after science decided that actually studying what they do in our bodies is a good idea, they discovered that maybe 10% of all of the millions of varieties of bacteria are actually harmful. The rest, either don’t hurt or they are really super duper useful.

Fun fact. Did you know that our cell mitochondria actually used to be a bacteria? It proved so useful to the healthy functioning of our cells that us and them eventually merged together. How cool is that?

The study of microbiomes is prompting scientists and doctors to think about health and sickness in different ways. Instead of viewing disease as a single entity, they are now looking at it as a disruption of the body’s ecology. At first it was believed that figuring out microbes would lead to all kinds of cures for diseases that had been troubling us for a long a time — obesity, allergies, immune disorders. Take a pill with the right microbes in it and your cured!

Of course it isn’t that easy, which is what is bringing science around to a systemic whole-body approach. They are learning that, depending on what microbes a person hosts, medicines will work differently. For instance, the popular antibiotic acetomycin, is completely ineffective for individuals who host certain microbes. Likewise other medications and treatments work better, worse, or differently than expected because of a person’s microbial ecology. The future of medicine is moving closer and closer to something more tailored to the individual rather than a one-size-fits all approach. It is still a ways off and likely to be expensive in the beginning, but that is where we are heading. My guess is that one hundred years from now people will look back at us and cringe in horror at how barbaric our medical practices are.

But the book isn’t just about people, animals and insects host microbes too and Yong takes us on a tour of some very interesting ones. A squid whose night time glow is due to its microbes. The discovery that termites can only digest wood because of the microbes they host in their digestive system. Hyenas use microbes to communicate with one another. Aphids can’t help giving off a certain scent because of their microbiome and certain parasitic wasps take advantage of that scent to hunt them down. And so much more!

I keep wanting to say fascinating! Bookman is probably glad I am done reading this because we’d be quietly reading in bed and I would suddenly shout, “WOW!” At the beginning of the book I almost set it aside because there were typos all over the place (kind of like this post – I hope I have fixed them all!). I was getting really super annoyed. As a reader, one or two typos in a whole book I can tolerate but it was getting ridiculous. I kept reading though because the material is so — fascinating. Eventually the typos disappeared. Perhaps they had a new intern proofreading the first few chapters or something, who knows?

The study of microbiomes is in its infancy and Yong does a good job on his whirlwind introductory tour. I Contain Multitudes is easy to read, well-paced, and, for the science geeks among you, super exciting (and fascinating!). Just keep reading past the typos, or wait for the paperback when they will hopefully have it all fixed.