I got turned on to gut bacteria a couple+ years back after reading a feature article in the NY Times Sunday Magazine.

While it didn't say so directly, a theory I took away from that article was that gut bacteria affects longevity. That is, couples live longer because they have more robust gut bacteria; pet owners much the same.

Might there also be an emotional component to a longer and healthier life? Absolutely. Humans are complex systems. Nonetheless, the science and data seem to also be saying The Gut plays a significant role as well. It will be interesting to see how pandemic isolation (as well as ongoing WFH) affects long term (gut) health.