https://www.quantamagazine.org/fish-have-a-brain-microbiome-could-humans-have-one-too-20241202/
I think the emphasis on "microbiome" in humans is a symptom of the psychopathic post-Christian Altruism that typifies modern Western (and especially leftist) thought. Even something as mundane as caring for your own health has to de-emphasize the individual and take the form of caring for a community.