I feel like just linking to the article that explained why gut microbiome research is so difficult.
By not needing measure the microbiome the testing pains are avoided. And though mouse models aren't human, they are effectively blinded.
Seems like a very worthy finding that adds to the legitimacy of microbiome's significance.
It'd be more interesting to compare different plausible microbiomes.
Maybe not in nature, but I wonder if it's a similar situation to human mothers who have recently taken a heavy course of antibiotics.
IIUC, that can somewhat nuke one's gut flora.