"The James–Lange theory refers to a hypothesis on the origin and nature of emotions and is one of the earliest theories of emotion within modern psychology. It was developed independently by two 19th-century scholars, William James and Carl Lange. The basic premise of the theory is that physiological arousal instigates the experience of emotion. Instead of feeling an emotion and subsequent physiological (bodily) response, the theory proposes that the physiological change is primary, and emotion is then experienced when the brain reacts to the information received via the body's nervous system." — https://en.wikipedia.org/wiki/James%E2%80%93Lange_theory
http://nautil.us/issue/56/perspective/antonio-damasio-tells-...
An excerpt can be found here: https://www.scientificamerican.com/article/gut-feelings-the-...
I recently found the theory of Lynn Margulis interesting, that we are all holobionts, not just relying on symbiotic bacteria but critically dependent on them, for breaking down food just as well as for staying healty. In that sense, we are less individuals and more landscapes, gardens that foster life.