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