I wasn’t planning on reviewing this on the blog. I didn’t think that a book on human microbiology would necessarily fit with the themes here. But I got ten pages in and changed my mind, and I shall tell you why.
First, I Contain Multitudes is about microbes. It tells the story of how they were discovered, when Antonie van Leeuwenhoek first noticed tiny creatures ‘very prettily a-moving’ in a drop of water. It was the 1670s, and nobody knew that microscopic life existed. As the world’s finest lens maker, Leeuwenhoek made microscopes that were ten times more powerful than anyone else’s, and he – alone in the world – had access to this unknown reality. And since he died without sharing his secrets, it was 150 years before science caught up with him.
That’s a great story already, but from those beginnings Ed Yong then details the growing understanding of microbes, the discovery of their role in disease, and the development of medicines to fight them. Because of their early association with disease, we’re suspicious of microbes. This, says Yong, is unfair. And we are only now beginning to get to grips with how important microbial life is for human health.
Our bodies are, after all, not ours alone. Adult humans have around 30 trillion human cells, according to the latest estimates, and 39 trillion microbial cells. What we consider to be ‘us’ is in fact an “ecosystem on legs”, and those microbes play a crucial role in our digestion, our immune system, and in our growth and development.
I Contain Multitudes is a great book, by a gifted science writer with – if you’ll excuse the expression – an infectious enthusiasm for his subject. The book is full of conversations with scientists and researchers, and it feels like a tour of an emerging field, full of incredible possibilities.
The reason I’m reviewing it here is that it is a remarkable demonstration of how interconnected everything is. The idea of human exceptionalism, that we are somehow above nature and special, doesn’t really make sense when we don’t even know where human bodies end and the microbiome begins. If we can’t even disconnect our own bodies from nature, how much less can we treat industry, civilization or the economy as separate from nature?
There is something humbling about recognising how inter-twined our own lives are with the microbes that ride around with us. We are ecosystems of interdependent creatures, and that too should give us pause when we start to talk about people as rational individuals competing for resources, or of competition as the natural state of the world. We’re not individuals, at a biological level. We’re more interesting than that. And life is far more mutualistic than we give it credit for.
Yong mainly sticks to the biology. He warns us not to get carried away with sentimental ideas about symbiosis, and rightly so. My point is not that nature has been cooperative all along. It’s more that if it was common knowledge that we contain more microbial cells than human ones, would we have to work so hard to convince people that conservation matters? Or that climate change is real? Or that the earth’s systems have natural limits?