The Evolution of the Sensitive Soul: Learning and the Origins of Consciousness by Simona Ginsburg and Eva Jablonka argues that a type of complex learning they call unlimited associative learning (UAL) is a marker in the evolutionary record for the presence of minimal consciousness. The book really is almost two books in one. The first part of the book has a historical survey of thought on the origin of life and consciousness that places the modern scientific viewpoint on consciousness into perspective. The second part addresses their main argument with a review of species and research on learning. It also includes the author’s models of associative and unlimited associative learning.
I first became aware of this work from the SelfAware Patterns blog which has an excellent three-part post that summarizes the work. Previously I had arrived at my own conclusions about learning, consciousness, and evolution before encountering a paper by the same authors that summarizes the main arguments.
I like this book. First, I agree with its main point about their being an association between learning and consciousness. More about that later. Second, the book assembles in one place a lot of material and research and learning and consciousness across species which one might find valuable even if not convinced of the main thesis.
The “sensitive soul” of the title can be traced back to Aristotle who distinguished three levels of soul:
- Nutritive and reproductive soul possessed by all living organisms
- Sensitive soul possessed by animals that feel and have experience
- Rational soul possessed by human beings
Their main concern is to trace the evolutionary development of the sensitive soul to discover what types of animals possess some minimal consciousness.
The term “minimal consciousness” is used extensively throughout the book and identification of its presence is the book’s main quest. Unfortunately, I am not certain this term or more generally the idea of gradations of consciousness is well-defined. Consciousness as we generally use the term always is consciousness of something. The problem is that almost all conscious organisms as identified by Ginsburg and Jablonka see, hear, smell, taste, and touch. Organisms do these things to varying degrees. Some birds can see magnetic force lines. Cats can see the ultraviolet. Bees see polarized light. Dogs can smell cancer. Bats and dolphins can navigate with echo location. Humans can do none of these things. In the sensual realm at least, do humans possess less consciousness than these other organisms? The contents of consciousness of a species are governed by the refinement of its sensual organs and the capability of its brain. Humans have consciousness not only of the sensual realm but also of a symbolic realm of language and abstract ideas. Does the symbolic realm arise from greater consciousness per se? Or, does it arise from unique, but unconscious, neurological capabilities in the human brain much like the bee ability to see polarized light is a product of special pigments in bee compound eyes? Does it make more sense to say organisms are conscious of different sorts of things based on their senses and brain without judgment on whether consciousness is greater or lesser in any organism?
Let us put aside that issue for the moment. Ginsburg and Jablonka argue that unlimited associative learning is a marker for consciousness. “Marker” seems to me to be somewhat of a weasel word. It is vague. It is saying there is association between learning and consciousness, but we are not actually saying what it is. On page 233, they ask the critical question: “How is this great expansion in the repertoire of learned behaviors and the cognition underlying it related to minimal consciousness?” In the paragraph that follows, they do not answer the question but return to their “marker” argument. Nowhere in their toy model for UAL is there a box for consciousness. No circle for consciousness surrounding some subset of functions. I cannot see anything in their model that requires consciousness.
Assuming UAL and consciousness are related, they could be related in the following ways:
- Consciousness enables UAL and is required for it.
- Consciousness and UAL are not causally related but when we get one, we get the other, perhaps because of some level of complexity in the brain.
- Consciousness and learning are the same process, similar processes, or both subsets of some larger process.
If the relationship is 1, we would expect to find a consciousness block somewhere in the diagram. If it is 2, then we are still missing something critical to explaining consciousness even if UAL gives us a key criterion for testing for its presence. If it is 3, then we could draw a big box or circle around the entire model and label it consciousness. Or we could say the model is a model of UAL and consciousness.
I lean mainly towards 3 with a hint of 1. I view consciousness as a system dedicated to aligning our mental representations with our inner states and the external world. This makes consciousness like learning since a key part of learning is achieving more useful representations of the world. I see major overlap between UAL and consciousness if they are not the same. It also might be that consciousness, to the extent it may be different from UAL, might be required for it.
Consciousness has causal power over our mental representations which guide our behavior. It may have direct control over neural circuits as some research with biofeedback suggests. Without causal efficacy, consciousness is reduced to an epiphenomenon and it is difficult to see how such a complex biological feature would emerge and persist across species through evolution. Learning is how this causal efficacy arises. This seems to be the view of Ginsburg and Jablonka, although I am not sure it is ever stated exactly like this in the book.
Finally, let me talk a little about a missed opportunity in the book.
If we step back and look at the big picture, we can see that the question of consciousness and its relationship to learning is actual a subset of the problem of how information accumulates in the world.
For the most part, everything in the world tends towards greater disorder, greater entropy. Locally in open systems, with external energy sources, pockets of order can emerge. Life itself is like this. Life does not break any law of physics, but as Robert Wright wrote: “Information is what allows life to defy the spirit, though not the letter, of the second law of thermodynamics.”
It is not entirely clear how this happens. If we knew how, we would understand the origin of life. I am not suggesting anything mystical, but we are probably missing some fundamental understanding of physics or chemistry.
Life is sometimes defined as entities that participate in the process of evolution by natural selection.
For Darwinian evolution to work, we need variation, selection, and ability to pass on traits. Variation means that entities can reproduce and when they do, they gradually change by mutation or otherwise. Selection means the changes can have consequences. Some changes result in fitter entities with better survival ability. Selection is by the eco-system in biological evolution. Finally, the entities must be able to pass on the changes.
Life itself – its genes and whatever else might carry information – uses information to multiply itself, to create its adaptive forms, and engage in adaptive behavior. Variation and selection produce new information -information for a better adapted organism and indirectly information about the ecosystem of organism. Leslie Valiant has compared the this evolutionary process to a computer learning algorithm except its performance evaluated against input it gets from a rather uncontrolled and unpredictable world.
If we return to Aristotle’s three souls, we see that each soul represents a stage in information accumulation that is driven by learning and evolution. The nutritive and reproductive soul evolves by a slow genetic learning process that requires generations for information to accumulate. The sensitive soul accumulates information through learning in near real time, in the life of the single organism, that can modify behavior for adaptive advantage. The rational soul takes learning into the symbolic realm to accumulate abstract knowledge and can record this information (because it is symbolic) to share it across generations.
In this light, the evolution of the sensitive soul and consciousness is one part of bigger trend and possibly a bigger mystery that began when life began.
