My "come to Jesus moment" on the importance of microbiome was a feature article in the NY Times' Sunday Magazine five or so years ago.

We always hear "People with pets live longer" and "couples live longer", right? While I can imagine the emotional value of those relationship and how it enables better health, my theory is that the constant presence of other microbiomes - human and/or pet - is also a major contributor to better health. Live alone? Without a pet? You aren't exposed as much.

p.s. Thanks for the book suggestion. I'll add them to my Wish List on ThriftBooks.com