In animals with brains, it is primarily the brain’s map of the body that monitors (through the nervous system) the state of the various subsystems that keep the body functioning (Damasio 2010). Since the body’s well-being often requires responses to events in its environment, parts of it (eyes, ears, etc.) are specialized to bring us news of what’s going on out there. Thus the brain’s map of the body includes an indirect mapping of the environment, or rather of the body’s relations with relevant aspects of it.Turning Signs, Chapter 3
But the most direct mapping of the body, and the primal index of its well-being (or ill-being), comes to consciousness in the form of visceral feelings – gut feelings in the true sense of the term. These arise from inside the body, not through the sensors in the eyes, ears, nose or skin but through the ‘enteric nervous system – the complicated mesh of nerves that is present in our gastrointestinal tracts’ (Damasio 2018, 60). In evolutionary terms, this is the oldest part of the nervous system, and the most intimately connected with the body it serves and regulates. Yet the digestive system is also inhabited by far more primal beings, single-cell life forms that vastly outnumber the human cells with which they live in symbiotic partnership.
In the human gut alone, there are usually around 100 trillion bacteria, while in one entire human being there are only about 10 trillion cells, counting all types.— Antonio Damasio, The Strange Order of Things (2018), 53
These bacterial cells are inside us but not of us in the way that the 10 trillion cells ‘in one human being’ are. However, all these lives share one basic tendency called homeostasis: they self-regulate to maintain a chemical balance within their bodies that is conducive to their well-being and flourishing. That tendency, much older than brains or nervous systems, is the core of whatever intelligence any life form has.
Bacteria are very intelligent creatures; that is the only way of saying it, even if their intelligence is not being guided by a mind with feelings and intentions and a conscious point of view. They can sense the conditions of their environment and react in ways advantageous to the continuation of their lives. Those reactions include elaborate social behaviors. They can communicate among themselves – no words, it is true, but the molecules with which they signal speak volumes. The computations they perform permit them to assess their situation and, accordingly, afford to live independently or gather together if need be. There is no nervous system inside these single-celled organisms and no mind in the sense that we have. Yet they have varieties of perception, memory, communication, and social governance. The functional operations that support all this “intelligence without a brain or mind” rely on chemical and electrical networks of the sort nervous systems eventually came to possess, advance, and explore later in evolution.— Damasio 2018, 53-4
Bodyminds with brains carry on the ancient homeostatic tradition by monitoring the state of the body’s interior, and representing that state in the form of feelings. Interoception is deeper than perception; our feelings about things and events around us are rooted in their relations to the state of the body, as represented to the mind by the images we call “feelings.”
Feelings are the mental expressions of homeostasis, while homeostasis, acting under the cover of feeling, is the functional thread that links early life-forms to the extraordinary partnership of bodies and nervous systems. That partnership is responsible for the emergence of conscious, feeling minds that are, in turn, responsible for what is most distinctive about humanity: cultures and civilizations. Feelings are at the center of the book, but they draw their powers from homeostasis.— Damasio 2018, 6
Damasio’s book proceeds to explain how feelings, ‘the most fundamental of mental states,’ give rise to subjectivity, consciousness, imagination, reasoning and cultural invention.
When feelings, which describe the inner state of life now, are “placed” or even “located” within the current perspective of the whole organism, subjectivity emerges. And from there on, the events that surround us, the events in which we participate, and the memories we recall are given a novel possibility: they can actually matter to us; they can affect the course of our lives.— Damasio 2018, 158
So, by Damasio’s account at least, gut feelings not only matter, they are the primal source of meaning for beings like us.