I regularly write about the microbiome – the trillions of bacteria that share our bodies with us, and the genes that they carry. At the recent International Human Microbiome Congress in Paris, I was immediately struck by two things. First, the field is clearly growing. It’s full of scientists who are doing great work to understand our bacterial associates, and who are glad that the microbes are finally hitting the big time. But I also felt a familiar twang. When one of the initial speakers described the quest to sequence our microbiome as the “biggest life sciences project of all time”, and when people spoke of new ways to diagnose and treat diseases, I was reminded about the hype that surrounded the Human Genome Project, back when our DNA had not yet been fully sequenced. When people showed communities of microbes that were associated with diseases, with no clear sense as to which caused which, I thought of the endless number of observational studies looking at risk factors for cancer, heart disease, autism, and other conditions. And it worried me. While I’m fascinated by the microbiome, and was thrilled to be part of the conference, I also wondered if the current optimism would lead to a backlash down the line. There’s precedent for this. The Human Genome Project is currently experiencing just such a backlash, as are large studies that try to find genetic variants that underlie human diseases. The so-called War on Cancer is still being fought several decades later, and patients are getting impatient. And I found many other microbiome scientists who shared my concerns, at the conference and beyond. This was the basis of a piece that I wrote for Nature News. It looks at the potential for hyping yet another ‘Big Science’ endeavour. But it also considers legitimate reasons why the microbiome may deliver on its promises more quickly than the genome has. In particular, diagnostic tests seem to be a rich area to focus on, with a good chance of providing short-term gains. Check out the full piece for more.