Famously, according to Douglas Adams, The Hitchiker's Guide to the Galaxy (not the novel, the 'actual' guide) begin by telling you at length how big space is, but then 'After a while the style settles down a bit and it starts telling you things you actually need to know' - and the opening of Ed Yong's exploration of the microbiome, the complex world of bacterial life inside us and generally in living things and around the world, is rather reminiscent of this. In the first couple of chapters, we are fed fact after fact in a staccato collection of information that has no sense of narrative or flow, rather like a set of frenzied bullet points, which becomes wearing for the reader. For example there are two paragraphs in a row, one with practically all the sentences starting 'They', and the next with almost all beginning 'We'll'. Thankfully, though, like the HHGTTG, We Are Multitude then settles down and gets on with job in hand.
It's a job that Ed Yong does very well. It's hardly news that we have many, many bacterial cells in us (though it does biologists no scientific favours when we discover the much used 'ten times as many as human cells' figure was just picked out of the air and has no scientific basis). However, Yong quickly takes us beyond that to explore the nuances of a very intricate relationship between bacteria and more complex life that could be summarised as 'Can't live with them, can't live without them.' Even many of our most hated bacterial foes can have positive roles at the right place and the right time. What certainly comes across is that our knee-jerk reaction of 'germs are bad' leads to an overemphasis on removing them, where actually they are often doing a useful job. When we go mad with our antibacterial cleansers, we are more like to wipe out good bacteria, leaving space for colonisation by nasties, than we are to simply kill off a threat. And Yong gives us a dramatic tour of the sheer variety of microbes and the environments in which different bacterial life can thrive, whether we talking black smokers or dolphin armpits. Every now and then, we get some excellent storytelling, but the use of example after example does give the impression to the non-biologist of the kind of approach that led Rutherford to comment that all science is either physics or stamp collecting - there is a fair amount of stamp collecting here. However, whenever the reader is beginning to feel that they are losing interest, up comes a really interesting part. I loved, for example, the story of the way that bacteria actually re-engineer the physical structure of a glow-in-the-dark squid. And it's hard not be impressed by the description of bacteria surveys being undertaken in a brand new hospital as it is brought into use, to see where the bugs come from. One of the particularly engaging observations is the emphasis on the benefits of open windows to allow bacteria to come in from the outside. Your mum's enthusiasm for getting you out in the fresh air was justified after all. If there's one message the reader comes away with, it's that we need to be more nuanced in our thinking about bacteria - sometimes, it seems almost to be a case of 'sit back and enjoy the ride, because whatever you do will probably mess things up.' You'll never look at a probiotic yogurt drink or a bottle of toilet cleaner the same again.