Antonio Damasio, author of Feeling & Knowing (2021), points to the whole body as involved in consciousness:
Prominent neuroscientist Antonio Damasio,considered “a leader in understanding the biological origin of consciousness,” wrote in The Scientist yesterday that “The idea that minds and consciousness might be generated by the nervous system alone is false. In his view, the whole body is involved in consciousness:…
Damasio’s approach to consciousness leans heavily on homeostasis, the constant self-balancing of a life form to stay in existence. Briefly, he argues for being, feeling, and knowing as three stages of the evolution of life forms, replicated in the intellectual development of a human being. Bacteria, which do not require a nervous system, exemplify being. Life forms that started around 500 million years ago (roughly, the Cambrian Explosion) feature feeling (and thus some level of consciousness): …
From the excerpt — which we must assume to be representative — Damasio accounts for human consciousness (“the word”) explicitly without any need for underlying intelligence in the universe (no “word”) by pointing to such features of life forms as homeostasis and avoidance of death. But he does not show how those features are a bridge to human consciousness. We want to account for Albert Einstein, Mother Theresa, and Gautama Buddha, — and innumerable others of our kind. Not for why humans, like amoebas, regulate our systems and strive to avoid death. Those may be mysteries in themselves but they are more tractable ones.
News, “Neuroscientist: Nervous systems alone do not cause consciousness” at Mind Matters News
Takehome: One-celled intelligence aside, it’s unclear how Antonio Damasio’s ladder of consciousness, built on self-balancing and death avoidance, gets us the human mind.
You may also wish to read: Why do many scientists see cells as intelligent? Bacteria appear to show intelligent behavior. But what about individual cells in our bodies?