Natural selection and the hard problem of conciousness

Philosophy of Mind
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So, an interesting realization occurred to me the other night while thinking about the philosophy of conciousness.

On the one hand, it is apparent that neural signalling correlates with the experience of “qualia” (ex. colours, feelings, sounds). Beyond this, however, we also see that the nervous system has a very unique kind of architecture where webs of tendrils (axons) carry, specifically, electrochemical discharges in various patterns. This is not only very different to the architecture we see in other biological tissues but is also the universal architecture used by all animals.

Assuming selection pressures favour animals having an internal experience of the world (which I think is a reasonable assumption to make, since experiencing one’s environment quaitatively, for instance, would improve an animal’s efficiency at distinguishing a predator from a food source or a tree/rock) then it is significant that natural selection produced an electrochemical signalling system as a means of achieving this fitness advantage.

I suppose one way in which we can explain this co-incidence is that electrochemical signalling is simply the fastest way to get a signal to the brain and produce the appropriate output. However, since transmission speed alone cannot close the gap between physical signalling and qualitative experience, the use of neural architecture by all animals seems to strongly suggest that electrochemical signalling taps into a qualitative modelling of the world in a way that other forms of signalling cannot.

I could be off the mark in this admittedly zoo-centric analysis. I personally don’t have a very deep knowledge of all the signalling systems used by plants or microbes, and if there is any persuasive evidence that such organisms may have faced a selective pressure toward internal modelling (i.e. “thinking”) then this would indicate that neuron-based signalling is not the only way for such a trait to evolve. I’d be interested to get some perspective from people with a more detailed knowledge of plant and microbial biology in this regard.

Edit: When thinking about how electrochemical signals could directly produce qualitative experiences, I imagined that the electromagnetic field might disturb or “pluck” some layer of reality similar to how a stringed instrument can generate different sounds by disturbing the air around it. I see this idea is pretty much equivalent to leading theories on the conciousness field
Ultimately, it seems far-fetched that qualia would be an inherent property of the action potential and the weak electromagetic field it produces, so I lean more toward a mechanism in which the field surrounding the signal disturbs a seperate field/medium.

Also, it is true that nervous systems aren’t absolutely uiversal to animals as we do not see this physiology in sponges. Given that sponges are sessile and are not able to maneuver away from threats in it’s 3-dimesional environment, there wouldn’t be any real fitness advantage to having an internal awareness of reality.

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One thing to note is that intelligence has evolved multiple times with similar but distinct neural architectures. Human neurology is different from that of octopi, which have effectively evolved intelligence independently of humans, but both have neurology nonetheless.

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If i’m not mistaken, octopi are capable of demostrating future-oriented planning, hinting at internal experience. Though I can’t recall a specific case off the top of my head.

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Cuttlefish, close relatives of octopi, have successfully negotiated (a modified version, of course, of) the Stanford marshmallow experiment.

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I am not sure what you mean by coincidence here - coincidence with what? Or are you just pointing out the fact that all nervous systems in animals are based on electrochemical signalling?

We don’t know whether the nervous system evolved only once or multiple times in independent lineages. If it evolved once very early on, canalizing further evolution along the original electrochemical principle of action, then there isn’t much of a coincidence to be explained.

In any event, it may just be the case that nature did not hit on any better, or even comparably suitable candidate. Evolutionary resources, after all, are constrained by existing chemistry and physics. Some functional requirements can be satisfied by multiple diverse mechanisms – like flying, for example. Others may only be afforded by one.

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What do you mean by “taps into”? I may be misinterpreting you, but it sounds like you’re saying the qualitative modeling is out there, and the neural architecture access it. Like maybe a geiger counter detects the radiation that is there whether the Geiger counter exists or not. And, consciousness, like a Geiger counter, gives us information that helps us?

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Yes, I also read that brains and even less complex systems probably evolved multiple times, but I was talking about the evolution of the most basic component of all these diverse nervous systems – the neuron. This review article from 2019 identifies the question of single vs. multiple origins as one of the unresolved questions.

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When searching for information on the common ancestry of animals, most sources indicate that the last common ancestor (the urmetazoan) probably lacked a nervous system, which would suggest that neural transmission is a convergent evolutionary trait which emerged multiple times independently.

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Aha, thanks for the link!

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I am thinking along the lines of some not yet verified/measured layer of reality. Like what is described in conciousess field theories. Patterns of neural activity on their own don’t seem sufficient to give rise to colours, tactile sensations, or various sounds and I’m skeptical that electrical discharges in the neurons carry properties that could give rise to experiences like “blue” or “hot” through additive effects.

This seems to leave a seperate component of reality which the nervous system can interact with. It may not be a field in traditional sense, but would carry the potential to produce qualia if disturbed or stimulated in the right way by electrochemical signals.

Of course, there’s no definitive evidence for such a model of conciousness and I can’t say I’m 100% cofident this is actually how it works.

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That article on consciousness field theories is interesting (also the further article on global consciousness field theories.) I’ve often posed the question that if there were fields analogous to electromagnetic fields but detectable only by organisms, then how would the existence of such fields be demonstrated? Electromagnetic fields can be demonstrated by their effects, but that employs a simple cause-and-effect logic. Whereas the possible effects of biological fields might be so subtle and their effects so complex, that it would be practically impossible to isolate and identify their causal roles even if they’re real. The deeper problem isn’t just causal complexity but the absence of any detector that isn’t itself part of what’s being measured.

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What the nervous system interacts with is, of course, the object of the experience. For example, the visible features of a chair made visible by available light and its wavelengths that cause electrochemical responses in the observer’s eyes.

Addition.
I’d say qualia is not modelled by the observer, instead it is the object of the experience that has the property of what it’s like. My experience of the chair literally is the chair, including what it’s like when I see it under such and such conditions of observation.

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I see. Thanks. I wish there was more on the ideas, and less about objections to them.

I agree, although I think the answer is that consciousness is fundamental, and a property of matter, just as things like mass and charge are.

I would be interested to hear more about this idea.

There is no definitive evidence for any model of consciousness, so you are in good company. :grinning_face:

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Can you explain? If the urmetazoan lacked a nervous system, that leaves the possibility of multiple origins open, but I don’t see how it makes it more likely than not.

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If they didn’t inherit a trait from a common ancestor, then they had to have developed it independently. When if it turns out to be the same mechanism.

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If we look at reflexes versus pain, the former is for stimuli where one, or a simple set, of responses is sufficient. Whereas pain has subjective experience (at various degrees of unpleasantness) and we can decide to withstand it to achieve a greater goal.

This seems a promising framing for all subjective experience – an abstraction that allows for complex decision making instead of needing fixed mappings of inputs to behaviors. And indeed to evolve each mapping.

Of course none of this is a disproof of p zombies.

It may be possible to make beings that behave like us without subjective experience, but nature went this way and it makes sense that it did.

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Definitely some good points brought up in the comments here. I wanted to elaborate on a few points. First, that we do see apparent behaviour outside of the animal kingdom such as phototropism in plants and threat avoidance in mobile prokaryotes.

I’m not a dedicated microbiologist or plant physiologist, I believe that among organisms that don’t have a nervous system, we know enough detail about the molecular processes that are happening to conclude that there is a necessary chain of cause and effect through the way molecules affect each other that a particular response necessarily results from a given stimulus. Something like a biochemical rube goldberg machine. Apparent learning in slime molds may be a bit more complicated. I need to do more reading on this.

Also, as far as the whole “automoton” idea: that apparently-intellegent animals like birds and octopi could be simple input → output machines that don’t have qualitative experience can’t be disproven given that we can’t experience what they do. Though given that each of us perform a lot of the behaviours that these non-human animals exhibit, and have concious experience when we do so, I believe the conclusion that qualitative experience experience occurs in other animals provides the most coherent and consistent model of the natural world. Otherwise we must conclude that the emergence of conciousess from our nervous system is a special case, which seems rather strange.

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Who are “they” and which common ancestor? The common ancestor of all animals probably did not have neural systems, but not all animals have neural systems, just as, for example, not animals have a spinal cord. Different phylogenetic reconstructions of animal lineages with and without neurons can suggest different conclusions with regard to their origin.

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If two species that have a common trait do not have a common ancestor with that trait, then the two species did not inherit their common trait from any common ancestor.

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Indeed, it does. It seems rather strange for consciousness to emerge at any point, regardless of the species, whether or not it had a nervous system, anything that would qualify as a brain, or neurons. If consciousness was not present before evolution brought about structure/system X, everything prior to X was purely physical in form and function, and X evolved because of purely physical mechanisms, it is far beyond strange that consciousness just happened to pop out. Why would X be the configuration needed for the emergence of consciousness?