Never Home Alone by Rob Dunn: A review

The full title of this book is quite a mouthful: Never Home Alone: From Microbes to Millipedes, Camel Crickets, and Honeybees, the Natural History of Where We Live. That's a tall order that the title promises to fulfill but Rob Dunn manages to do it.

The aim of his book is to explore the biosphere that comprises all the critters that live on and in our bodies and that share our houses with us. After years of sampling and cataloging this biosphere, he and his colleagues found what he describes as a "floating, leaping, crawling circus of thousands of species," perhaps as many as 200,000 altogether. Many of their discoveries were previously unknown to science.

Dunn and his team sampled and analyzed such areas around the house as shower heads, door frames, refrigerators, hot water heaters, cellars, toilets, pillowcases, and the list goes on and on. Some of the findings are rather disgusting and occasionally alarming but always fascinating. The bottom-line finding of their research is that most of our fellow travelers and cohabitators are either benign or actually beneficial to us in some way. Only a few are actually harmful. 

The problem is that we have become so paranoid about making our living spaces as pristine as possible, using pesticides and antimicrobials and sealing off our homes from the outdoors, that we have upset the balance between the good guys and the bad guys. In fact, we have tipped the scales in favor of some of the bad guys.

The microbes that live with us are able to evolve incredibly fast. They adjust to live in ecological niches which we can hardly even imagine and thus they are able to survive our chemical assaults against them and to evolve their way out of every trap we set for them. That is how we get pesticide-resistant German cockroaches and bedbugs as well as antibiotic-resistant bacteria. 

The research team's findings regarding our indoor biosphere is much the same as ecologists' findings about the larger environment: Biodiversity rocks! The richer the diversity of life in our houses the better. A diverse biosphere keeps things in balance; the benign, the beneficial, and the detrimental fill their appropriate niches and an equlibrium is achieved. 

One interesting hypothesis arising from the team's research concerns the relationship between a degraded and less diverse biosphere and the incidence of certain inflammation-associated diseases such as Crohn's disease, asthma, allergies, etc. They found a correlation between areas where the biosphere had been interfered with (i.e., excessively cleaned) and a higher incidence of those diseases. They had not set out to prove any such link, but their findings were highly suggestive. All of which led me to wonder about environmental factors related to some other diseases that are rampant in our modern society - things like autism, e.g.

There's a lot to digest here and Dunn makes it all perfectly palatable. His writing has a kind of folksiness quality to it. He keeps it all on a level that would seem to be easily understandable for the average reader. He's writing for the general public, not for his fellow scientists, after all, and his goal is to proselytize for the preservation of biodiversity, not only in our larger world but also in those smaller spaces where we live our daily lives. 

I did have one quibble with his book. In listing critters that share our houses with us, he kept referring to things like cockroaches, mosquitoes, silverfish, bedbugs, and spiders, and he repeatedly referred to them all as insects. I was quite offended on behalf of our friends and allies, the spiders.

Since reading this book, I have noticed one effect it has had on my behavior: I now wash my hands more often and more assiduously than before!

My rating: 4 of 5 stars 


  1. Oh boy! The things we share our space with... :-)

    1. Their numbers are legion. We are truly never home alone.

  2. I had not come across this book anywhere. I have certainly had similar thoughts about our hyper-clean habits and disease. I am ok with sharing space with spiders but I draw the line with ants!

    1. We all have our red lines, I guess. I'm not fond of roaches, but I do love and defend my spiders!


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