The symbiotic relationship between Humans and their resident Microbiome (especially the gut microbiome) is already a well-studied subject. But it can certainly do with more popularization :-)

Some References:

1) Role of the Microbiome in Human Development - https://pmc.ncbi.nlm.nih.gov/articles/PMC6580755/

2) Human Microbiome Project - https://en.wikipedia.org/wiki/Human_Microbiome_Project

3) The Human Microbiome Project: Exploring the microbial part of ourselves in a changing world - https://pmc.ncbi.nlm.nih.gov/articles/PMC3709439/

4) The Human Microbiome: From Symbiosis to Pathogenesis - https://pmc.ncbi.nlm.nih.gov/articles/PMC3731629/

5) The Second Brain: A Groundbreaking New Understanding of Nervous Disorders of the Stomach and Intestine by Michael Gershon. This is a must-read neuro-psychology book.

6) Gut: The inside story of our body’s most under-rated organ by Giulia Enders. Another must-read book.

7) Finally; i came to know (have not browsed/read) of this definitive textbook Fundamentals of Microbiome Science: How Microbes Shape Animal Biology by Angela Douglas (via her Microbiomes: A Very Short Introduction Oxford series book) - https://press.princeton.edu/books/hardcover/9780691160344/fu...