This was a pick by one of the two book groups I’m in and I’m wondering why. Published in 2016, it’s already well out of date. Reading it is like coming across someone’s newspaper clippings on the subject of microbes they compiled from 2010 to 2015. Much of what’s in this book has been covered and updated in the semi-popular press.
 There are other problems with it.
• The title is misleading. You think it’s going to be all about the microbes humans carry inside them, but at best, just twenty percent of it’s about that. Most of it is about microbes in general, and we learn a lot about microbes in insects. For some reason, there’s a long part about the degradation of coral reefs, an important topic, yes, but it’s been well covered elsewhere.
• There are far too many notes (376 over 264 pages), and you don’t know which ones add enough to the text to bother flipping to versus ones that just provide citations without reading them. You can try looking at the notes before beginning a chapter and remembering when to go to the ones you should read, but that’s hard. (Was it 23 or 25?) Many of the notes could have easily been incorporated into the text without breaking the flow or slowing things down. Doing it the way Yong has makes the book seem like a weird mix of academic writing and popular science writing. He clearly tried to make it readable to the layperson, which you can tell by the title and by the way all the chapter titles are either directly or derived from familiar phrases.
• There are more errors and typos than I like to see in a professionally published book like this, but that’s the old crank in me speaking. For much of one chapter, the note numbers and the notes don’t match.
• Much of what is advocated in this book is laughable now due to the pandemic, as sound ideas as they may be. It’s unlikely that anyone these days will try to incorporate more bacteria into their lives than they do now. In one passage, Yong even suggests that cleaning toilets as often as we do does more harm than good, a concept no single man should ever hear.
 When the book is good, though, it is informative.
 An excerpt:

To control a microbiome is to sculpt an entire world—which is as hard as it sounds. Remember that communities have a natural resilience: if you hit them, they bounce back. They are also unpredictable; if you tweak them, the consequences ripple outwards in capricious ways. Add a supposedly beneficial microbe, and it might displace competitors that we also rely on Lose a supposedly harmful microbe, and an even worse opportunist might rise to take its place. This is why attempts at world-shaping have so far led to a few magnificent successes, but also many puzzling setbacks.