Consciousness and Intelligence in “Simple” Organisms: You Can Come Home, Edward Heron-Allen

Previously on this blog, I considered some of the implications of the complex behavior of single-celled organisms when I discussed agglutinated foraminifera.  These species of marine foraminifera construct their “shells” out of material their pseudopod-like filaments find in the surrounding substrate; this found material is then cemented together in very precise, species-specific configurations.  A fossil from one such species dating from the Miocene is shown below.

It was argued by some, beginning in the last quarter of the 19th century, that this behavior may demonstrate a form of rational behavior, intelligence, if you will.  I highlighted the position staked out early in the 20th century by Edward Heron-Allen (1861-1943), one of the leading foram experts at the time (and a favorite character of mine).  Heron-Allen was a polymath who wrote fiction, acted, and made violins, among other pursuits.  (The image below of Heron-Allen has no apparent copyright restrictions and is from the Division of Rare and Manuscript Collections, Cornell University Library.)

Heron-Allen also excelled at taxonomic research on foraminifera along with his colleague Arthur Earland (1866-1958); both were unpaid amateurs working at the British Museum.  Heron-Allen, inspired by the accomplishments of agglutinated foraminifers, argued in a 1915 paper, that:

there appears to be no organism in the Animal Kingdom, however simple be its structure, which lives a life of its own independently of any other organism, which is not capable of developing functions and behaviour (including the adaptation of extraneous matters to its use and protection), which in the Metazoa might be called, and would be properly be so called, Phenomena of Purpose and Intelligence.  (A Short Statement Upon the Theory, and the Phenomena of Purpose and Intelligence Exhibited by Protozoa, . . . .   Journal of the Royal Microscopical Society, 1915, p. 556.)

This argument, that all independently living organisms, no matter how simple, could exhibit signs of intelligence, was mocked and beaten back by the scientific community in the ensuing years.  But (ah, the all-important “but”), to date, no consensus explanation of how these forams accomplish this task has been put forward.

Today, I suspect, his contention would find favor in a segment (small, I assume) of the scientific community.  Why that might be is the subject of the present post.  I stumbled onto this topic after unknowingly coming close to it in my previous post on fungi.  In that post, I wrote the following, regarding the network of hyphae or filaments (this network is called the mycelium) that many fungi spread underground:

I find it fascinating that, rather than relying on something like chemical detection in the quest for food, the mycelia use brute strength, “spread[ing] outwards in all directions until they strike digestible objects.  When this happens the colony reacts by redirecting growth towards these locations” [quoting Nicholas P. Money, Fungi:  A Very Short Introduction, 2016].

I missed what biologist and mycologist Money was suggesting in that quotation of his.  That the colony reacts and “redirects growth” more fully toward food sources now has a meaning for me that it didn’t before.  Shortly after writing the fungi post, I found a link in my inbox to a recent article by Money that spelled out what I had missed:  The Fungal Mind:  On the Evidence for Mushroom Intelligence, Psyche, September 1, 2021.

As I began exploring topics discussed in Money’s article, I found myself drowning in a sea of undefined or poorly defined terms.  I did something that Money didn’t do (and others often don’t either, particularly in popular science articles):  assemble definitions of a few of the key terms.  Given below are the common definitions of these terms as provided by the Oxford Compact English Dictionary (2003):

• consciousness = state of being “aware of and responding to one’s surroundings”

• sentience = the ability “to perceive or feel things”

• cognition = “the mental acquisition of knowledge through thought, experience, and the senses”

• intelligence = “the ability to acquire and apply knowledge and skills”

I will admit that this exercise in definitions intended to clarify matters didn’t help much.  I remain confused and largely unable to distinguish one from the other (in this I am not alone).

In his piece, Money writes:

[I]n recent years, a body of remarkable experiments have shown that fungi operate as individuals, engage in decision-making, are capable of learning, and possess short-term memory.  These findings highlight the spectacular sensitivity of such ‘simple’ organisms, and situate the human version of the mind within a spectrum of consciousness that might well span the entire natural world.

He describes a number of these experiments particularly some involving the behavior of fungal mycelia.  They are highly suggestive.  He posits that mycelia “actions draw upon an array of protein sensors and signalling pathways that link the external physical or chemical inputs to cellular response.”  Though he acknowledges that the fungi “are not thinking in the sense that a brained animal thinks,” he asserts that “the fundamental mechanisms that allow a hypha to process information are the same as those at work in our bodies.”

I was particularly taken by the results of one laboratory experiment which involved the behavior of hyphae.  When those emanating from a fungus encountered a piece of beechwood, they broke it down and then spread out in search of more food.  When the mycelium encountered a second piece of beechwood and exhausted its nutrients, it began foraging from this second piece in the same direction that had borne fruit when it went foraging from the first.  Memory at work?  Money certainly thinks so:

It remembered that growing from a particular face of the woodblock had resulted in a food reward before, and so sought to repeat its prior success.  The fungus in these experiments showed spatial recognition, memory and intelligence.  It’s a conscious organism.

Tellingly, Money does not restrict his discussion to fungi (despite the title of the article), turning to research on slime mold, that poster child for researchers claiming consciousness and intelligence in single-celled organisms or collectives of single-celled organisms.  It’s not surprising that he does so; the experiments involving slime molds are breath-taking (perhaps even more impressive than those involving fungi), certainly challenging one’s expectations of the capabilities of such organisms.

Although slime molds continue to be placed in the Kingdom Fungi by some authorities, the preferred placement appears to be the Kingdom Protoctista (Protista).  Aspects of their life histories might be seen as fungus-related - they have a spore stage by which they spread, while other aspects are protoctista-like – when the spore germinates, a single-celled, amoeba-like organism emerges and goes in search of food.

There are three taxonomic groups of slime molds.  (See University California Museum of Paleontology, Introduction to the “Slime Molds”.)  One group, the plasmodial slime molds, appears to be the primary type used to demonstrate intelligence in these single-celled organisms.  This plasmodial slime mold may start as a tiny amoeba-like single-celled entity with a single nucleus, but, over time, through the fusion of individual slime mold cells, grow quite large, becoming one cell harboring countless nuclei.  The organism accomplishes its search for food by spreading a thin film, called the plasmodium; when the plasmodium encounters food, some of the plasmodium may concentrate into tubular channels, creating a network to transport nutrients.

Writer and English professor Lacy M. Johnson has written about Fuligo septica, commonly called “dog vomit slime mold” (What Slime Knows, Orion Magazine, no date).

Here in this little patch of mulch in my yard is a creature that begins life as a microscopic amoeba and ends it as a vibrant splotch that produces spores, and for all the time in between, it is a single cell that can grow as large as a bath mat, has no brain, no sense of slight or smell, but can solve mazes, learn patterns, keep time, and pass down the wisdom of generations.

(Dog vomit slime mold is shown below in a photograph by Henk Monster which is reproduced here under the Creative Commons Attribution 3.0 Unported license.  It can found on Wikimedia Commons.)

One of the experiments involving slime molds that Johnson, among many others, describes was performed by a team of Japanese and British researchers (Atsushi Tero, et al., Rules for Biologically Inspired Adaptive Network Design, Science, January 22, 2010).  It’s a classic.  In this experiment, an array of food sources (oatmeal flakes) were disbursed across an area that Physarum polycephalum was able to explore.  As the slime mold, which started in the center of the area, spread its plasmodium throughout the area encountering other food sources, it created, in relatively short order, a network of emphasized connections linking the food sources.  The image below shows the network being created by the slime mold, linking the various caches of oatmeal flakes over a 26 hour period.  At the end, the less effective pathways have faded away and only the most effective remain in play.  (The image is provided by TimTim and reproduced under Creative Commons Attribution-ShareAlike 4.0 International license.  It can be found at Wikimedia Commons.)

In this experiment, the distribution of food sources was not random, rather, it was designed to represent Tokyo (at the center) and surrounding rail stations.  Turns out the network created by the Physarum is remarkably similar to the actual configuration of railway tracks that link these stations.  In a brief video, botanist Mark D. Fricker at the University of Oxford, a member of the research team, shows how the slime mold behaved in this experiment.  (BBC Earth Lab, Can Slime Mould Solve Mazes?)  Well worth watching.  Intelligence at work or a neat parlor trick?

In his article, Money notes that the consideration of consciousness in so-called simpler organisms raises the core question of what we mean by consciousness and which living entities have it.  (No definition is forthcoming from him.)  Understanding consciousness and the organisms in which it is found is important, because I read Money as saying “if no consciousness, then no intelligence” (which stands to reason).  He asserts, consciousness “implies” awareness which, in turn, manifests itself in an organism’s sensitivity to its environment.  Though all living creatures exhibit sensitivity, consciousness has traditionally been reserved for just a fraction of those creatures, the so-called big-brained animals.  In challenging that hierarchical approach to consciousness, Money cites cognitive psychologist Arthur Reber who posited it was impossible to identify the minimal level of awareness necessary for consciousness.

That sent me in search of material by Reber.  He and František Baluška recently penned a fascinating article that asserts that all living cells are “self-aware, self-organizing.”  Indeed, they argue that, because “sentience was a property of the first forms of life that emerged some 3.5 billion years ago, all species, extant and extinct were and are sentient.”  (Cognition in Some Surprising Places, Biochemical and Biophysical Research Communications, 2021.)  This had to be, they argue, because the first cells could only survive if they were, to some degree, able to respond to the “constantly shifting complex flux that marked the primordial environment.”

Further, they assert (as Money describes above), if the earliest cells were not sentient, then at what point did “a species or clade [shift] from being utterly without internal experience, consciousness, to one with it?”  Reber and Baluška juxtapose their assertion about sentience in the earliest living cells with a quotation from evolutionary biologist Lynn Margulis:  “cognition is a biological function.”  That’s an important connection.  The authors, who equate sentience with consciousness, are here, most importantly, also equating sentience with cognition.  To them, it's apparently “if yes consciousness, then yes cognition.”  How much of a step is it to go from cognition to intelligence?  Does cognition raise the possibility of intelligence or the certainty of it?

Reber and Baluška are proponents of the Cellular Basis of Consciousness (CBC) hypothesis which posits:

that sentience and life are coterminous; that all organisms, based on inherent cellular activities via processes that take place in excitable membranes of their cells, are sentient, have subjective experiences and feelings.  (Abstract of the article.)

This is a heady position to take, one that serves as a lightning rod for criticism.  See, for example:  Peter Jedlicka, Review of “The First Minds” by Arthur S. Reber, 2018, OUP Global Press:  New Consciousness Theory:  Cellular Basis of Cognition or Consciousness?, BioEssays, Volume 42, 2020; or Simona Ginsburg and Eva Jablonka, Review:  Are Your Cells Conscious?, The American Journal of Psychology, Vol. 133, No. 1, Spring, 2020.

But what a provocative hypothesis to argue over, if only we could nail down our terms.  Nevertheless, it's lovely that this all harkens back to Edward Heron-Allen who over a hundred years ago asserted:

every living organism living an independent existence of its own is endowed with the measure of intelligence requisite to its individual needs.

I must admit, in closing, that perhaps the one certainty emerging from all of this is that I have confused consciousness with sentience and cognition with intelligence.  Are these different?  How so?  Are they actually manifested in these "simple" organisms?  For me, sadly, these terms have all merged into a blob of slime mold.