John Z. Young, Cephalopod Brains, Homeostasis and the Unreality of the World

John Z. Young (1907-1997), a zoologist and neurophysiologist specializing in the nervous system of cephalopods, developed his view of models, learning, and the mind in a number of his published works, but particularly in A Model of the Brain, in 1960 and Philosophy and the Brain, in 1987. He discovered the giant axon inside the brain of cephalopods which was so essential for understanding how human minds work. Interestingly enough, he was also a descendant of Thomas Young (1773-1829), the famed British polymath. Young’s way of thinking about homeostasis and how we develop ways of interacting with the world is decidedly Neo-Kantian, though he never had much formal philosophical training, and was derided by the legion of academic philosophers during his own time. While it’s true that his thought was not always the most rigorous or deep, it nevertheless bears some serious consideration.

His neurological and evolutionary understanding of mental models, their behaviour and function casts doubt on their capacity to demonstrate unmediated, objective reality. What we can only say about them is that they represent how complex organisms come to know things, but that their role outside of basic survival towards some higher truth is questionable. The Kantian and neo-Kantian influence on this thought is also evident, and will help to explain both his view of perception as an active part of the life of an organism and how he reconciles his belief in a real world with the convenient fictions of evolved perception.

In What Squids and Octopuses tell us about Human Brains he expresses his dissatisfaction with the language of action potentials and nerve impulses because he thinks that they are ambiguous and evasive terms that only serve to mask the fact that physiologists do not know what these impulses communicate within the nervous system. Young’s issue with the neurological discourse of his time is similar to the “illusion of understanding” mentioned by Craver in the case of black boxes, and filler terms. What is even more striking is that Young’s own evasive critique seems to be directed towards figures such as Andrew Huxley and Alan Lloyd Hodgkin, who won a Nobel Prize in physiology or medicine for their model of how neurons behave. Yet as Young says:

“curiously enough the physiologists who win Nobel Prizes for the study of nerve fibres seldom, or never, use words such as ‘code’ or ‘symbol.’ They stick to the dear old terms ‘nerve impulse’ and ‘action potential.’ They have indeed been able to find out a very great deal about the physical changes that are involved in the transmission of the nerve message, without thinking much about what the message communicates. To be unkind one might say it was like giving a Nobel Prize for Literature to people who had advanced knowledge of typewriters, or of ink, or perhaps of radio transmission!”

This critique is an unusual one, especially considering Huxley’s and Hodgkin’s own attitude towards their model. As Craver has made clear, neither of them claimed that it was representative of reality, but only served as an important groundwork for further investigation. Yet before we disregard Young’s claim as the product of academic jealousy, it is wise to consider whether or not it has any substance. In many ways their self-conscious use of models is beside the point for Young, since even then their accomplishment serves to perpetuate physiologists ignorance about the actual activity of the nervous system, which for him rests in what is communicated, not how it is done. Here Young points out that:

“The trouble is that in the more interesting parts of the brain we cannot specify what the ‘function’ is. So when we say that when we see red certain nerve fibres from the eye transmit something called nerve impulses we do not really know what we are saying. In what sense do nerve impulses transmit redness?”

Instead, we need to come to an understanding of how the nervous system serves for communication, and how it represents symbols to the organism.

The only way out of the black box that Young sees in the study of action potentials and nerve impulses is to treat them as codes in a larger system of communication. As he says:

“The significance of signals in a code is that they symbolize the matters to be communicated. If we are to describe the effects of our nerve impulses properly, in this analogy we must say that they are significant because they are symbols, that is, they stand for or represent either some event in the outside world or some inner need or some action to be performed at the decoding end of a communication channel. We say that a sign or a signal becomes a symbol or representation for something else when it has the effect upon us of that something.”

The operation of nervous systems as such, then, is to represent some external or internal change for an organism or provide instructions for action from the brain to some muscle or gland. Young sees these representations as models built up within the organism, but before we can discuss these models in detail, it will first be necessary to see his view of the organisms that make use of them.

For Young, the essential feature of all organisms rests in the relationship between their internal condition and that of the environment around them. The primary quality that separates them from other systems is that they are homeostats, systems which strive to maintain a steady state, as opposed to inanimate objects whose conditions fluctuate along with that of their surroundings. The most effective homeostats will be those who have some way of acting in response to changes in their environment.

It is for this reason that the development and function of the nervous system plays such an important role in his thought. The primary function of all nervous systems, from that of the lowest worm to that of the human being, is to regulate and manage inputs from the environment and propose outputs, or actions, in response in order to maintain this steady state. As Young points out:

“Like all representations in codes, models in the nervous system are used for transmitting, storing, or manipulating information that helps in making predictions by which homeostasis is ensured. In particular, the conception often, though not necessarily, contains he idea of something that ‘works’.”

An example of this feature in cephalopods can be seen in the way that their statocysts allow them to respond to gravitational forces. As Young says:

“To meet the task of correct orientation in relation to the earth’s surface, there is present in the statocyst a little model to represent gravity, a stone hanging upon sensory hairs. These hairs send streams of action potentials whose pattern thus symbolizes the position of the animal in relation to gravity. […] If the statocysts are destroyed this is no longer possible. Notice, then, that the model serves to allow the action system of the animal to maintain its proper relation with the rest of the world- the essential feature of living.”

The power of the nervous system of most organisms rests in its ability to create models of the individual’s environment that serve as a means of survival. The more effective the individual’s nervous system is at representing those features of its environment that are vital to life, the more successful the organism will be.

To help facilitate homeostasis and survival, organisms actively seek out specific inputs that apply to their internal models. One of the most striking consequences of this is that their perceptions, rather than passively taking in the environment, come to play an active role in what organisms perceive, “looking” for some stimuli, while ignoring others. Taking traditional views to task, Young comments that: “in most observations about perception made by psychologists and physiologists or considered by philosophers the stimuli are given to the human or other organism, not sought out as they usually are in life”. However, passivity is not the case, and he defines perception as the active search by organisms for the ordered features of their environment, or information, that is relevant to maintaining the homeostasis of their life processes. As Young states, this property of living things is universal:

“Each type of animal has transducers that are appropriate to its environment and mode of life. This already places restrictions on what can be perceived […]. Each species has analysers which reorganize the signals received form the transducers and select among them so that they will report features that are relevant for its life.”

The consequence of this is that the way things appear is never merely a function of their individual nature, from the simplest observation to the most specialized analysis.  Furthermore, it is exactly because models are the basis of the nervous system that perception is selective in this way, and has its part to play in what is selected by evolution and through learning.

The model-based structure of organisms as homeostats has consequences for how we view both evolution and the individual. On the level of evolution, Young believes that natural selection largely selects based upon the fit of organisms’ internal models with their environment, so that the process of evolution itself can be conceived of as an evolution of models. This is why he can say that:

“As the result of a process of natural selection the inherited DNA of every individual provides for the formation of a creature able to live under certain conditions. In this sense we can say that the DNA is a representation of that environment. The organism that it produces literally re-presents actions appropriate to those conditions.”

Thus Young’s neurological view of model building in organisms applies just as much to complex animals as it does to the organic molecules that compose them.

Reflexes are a particularly good example of the process of evolutionary selection of models in the nervous system. He uses the example of the reflex to pull one’s hand away from a very hot object, which is valuable both because of its clearly genetic basis and because the process itself does not take place in the brain, but in the spinal cord:

“it is clear that the arrangement of all these sensory fibres and synapses and nerve cells serves as a representation of the actions that are likely to be effective after contact of the skin with a very hot object. […] The spinal cord is capable of thus computing an avoidance response, a type essential for survival, without reference to the brain”.

However, the kind of modeling performed by reflex responses is limited to within a relatively set range of environments, and relies upon the sometimes-false premise that the future will resemble the past. A more elaborate method of modeling is seen in learning.

On the level of the individual, learning is the process whereby organisms come to develop new internal models based on their experience in their own lifetime. Young summarises the essence of learning in biology as:

“the attaching of symbolic value to signs from the outside world. Images on the retina are not eatable or dangerous. What the eye can provide is a tool by which, aided by a memory, the animal can learn the symbolic significance of events. The record of its past experiences then constitutes a program of behavior appropriate for the future.”

This “program of behavior” is the development of an internal model which represents certain key features of an organisms environment, but which allows for the establishment of yet further models through individual experience. It is the success of this method in evolution that contributed to the increase in complexity of the nervous system of the “higher” animals, even at the cost of a much longer period of growth than in organisms with simpler systems. In many ways the evolutionary success of the nervous system highlights the active nature of perception previously discussed. As Young elaborates: “All animals make some form of search for their livelihood (indeed so do plants), but the ‘higher’ animals must seek for and find a much more elaborate world than is available to the ‘lower’, because they exist in conditions that are less directly suited to the support of life”.

Furthermore, the process of learning in an individual reciprocates the process of model development through evolutionary means. As Young points out: “It is clear enough that the two methods must stand in some reciprocal relationship. The better the means of repair, adaptation, and learning, the less often will it be necessary to undertake a basic revision of the instructions of the homeostat”.The understanding of organisms as homeostats with a vested interest in regulating their inputs, perceptions, and outputs, actions, allows these learned or inherited internal models to function in much the same way. Both systems of model development function by means of interpreted codes from within the organism and from the environment. In the case of the nervous system, natural selection has often selected for the refinement and multiplication of any kind of model that re-present those features of a homeostat’s environment that are essential to its life. This demand, as well as insuring the development of models that help the organism maintain homeostasis, also puts limitations on what can be perceived and known, often, if not always, for the purpose of survival. It is to the historical precedent of these limitations that we now turn our attention.

Even thought Immanuel Kant makes few personal appearances in Young’s works, it is clear from his discussion that his thought resonates with many Kantian and Neo-Kantian undertones. Kant is only mentioned by name in four places in Philosophy and the Brain, although Young often discusses perception in a very similar vein to his idea of representation and clearly states that it (vorstellung\representation) was a term used by the philosopher. Young’s study of perception, particularly vision, also brings him into many of the same realms as Hermann von Helmholtz, who was himself a Neo-Kantian. This is particularly evident when we consider his comments on the selectiveness of perception, for, as he says:

“These facts [about perception] are fundamentally important for philosophers. They provide direct evidence that what is perceived is selected largely unconsciously as a result of the history and activity of the perceiver. This was recognized long ago by Helmholtz.”

Despite the scarcity of direct references, the content of Young’s evolutionary and neurological analysis of perception possesses many of the salient features of Kantian thought, such as the relative inaccessibility of the thing-in-itself, the ordering limitations on human thought, and the active nature of perception as previously mentioned. This similarity is further highlighted by a consideration of his thought on the senses of sight and hearing.

After discussing the process of hearing and how it is interpreted by the “models” within the human nervous system, Young questions its ability to provide “true knowledge of the pattern of variation of air pressures”, and concludes that: “A naïve realist would be hard put to it to show that with immediate data of auditory perception we acquire valid knowledge of reality without any interposing ‘ideas’ or other such entities”. By “interposing ideas” he means the active models of reality that have developed in the nervous system both through evolution and learning to facilitate the survival of the homeostat called the human being. The demand for an unmediated sense of reality, then, ignores the evolutionary and physiological basis of humanity, attributing to its perceptions a direct connection to the essence of things which they do not possess. The situation is much the same for vision, with the added evidence of the blind who have later been given the ability to see, but who have not developed the internal models that seek out and interpret the salient features of their new visual environment. Here Young is blunt about the indirectness of the information received through vision, saying that:

“The very daylight we see is our own creation. What falls on the retina is a flux of electromagnetic radiation, which is absorbed in steps called quanta or photons. […] What the observer perceives, people, trees, houses and the rest, is selected from those patterns by programs [models] learned since birth because of their significance for him. People who have been born blind and are later given sight by an operation find that they can ‘see’ light, but none of these other things. They may see a confused mass of colours […]. Later they may learn to see shapes.”

As the case of the blind demonstrates, and as Young has often repeated throughout his writings, while the eye itself may function like a camera, the faculty of vision, the process of interpretation that makes it relevant to the life of the homeostat, certainly does not.

Young understands that the evolutionary nature of perceptions may place limitations on what we can know, and that we may not be able to go further beyond these mental models. As he says near the end of Philosophy and the Brain, these limitations can be partially overcome, for example, by developing instruments that allow us to “perceive” things such as ultra-violet light. However, there may also be some major practical limitations placed on the way that the brain can be used to think and reason: “At several points it has been emphasized that there is evidence that the brain may be organized on a basis of the use of certain concepts, for instance about order and space”. It does not seem likely that Young should mention order and space as fundamental categories of human perception without knowing that it was just these qualities (order in time and space) that Kant described as two of his own a priori categories of understanding. In the case of his own biological interpretation, since the underlying models upon which human experience is based have been selected exclusively as a means for survival, there is no definitive way to dispel scepticism about the “ultimate” origin of our perceptions. However, much like Kant, Young stresses that there is a reality underpinning them:

“There is little doubt about the veracity of the resulting perception. The person who has trodden on a sea urchin has indeed detected a small spiky section of the universe, thought he learns nothing about its shape or extent: it might be a sea urchin or a broken bottle.”

Elsewhere he likewise comments that: “one can hardly avoid hearing a clap of thunder, nor can one reasonably doubt the ‘reality’ of the noise”. From these comments it is apparent that Young is not a relativist in the traditional sense of the term, but that his understanding of models in human thought and perception does preclude any pure, unmediated knowledge of the world, or, in its Kantian articulation, the thing-in-itself.

If Young’s account of the relationship between modeling, organisms and their environment is sound, it would have profound epistemic consequences. What would this understanding of the human brain as a system of models mean for the human capacity to construct their own models of the world? For if the function of the nervous system is primarily to look for certain key features of the external environment at the expense of others, and our own models are likewise limited to certain key features, then both the resulting phenomenological or explanatory model can said to be at best twice removed from any ideally conceived form of objective reality. Furthermore, when this kind of human understanding is seen within its neurological and evolutionary context, what we call knowledge or explanation would then only be a way of discussing some kind of process of survival or procreation, albeit, one removed from the traditional meaning of the term “survival”.

In his entire discussion, Young stresses the need to place human reasoning on the same continuum as that of animals, that this has not been done by philosophers of his day, and that from this position some of our deepest epistemological commitments must necessarily be shaken. Survival in the case of human modeling of the world, however, is not always to be construed in exactly the same way as we see basic animal survival. Young began writing in this vein in the 1960s, though his thoughts culminated in 1987. The discussion of memes first began in 1976 with the publication of Richard Dawkins’ work The Selfish Gene. What is striking about Young’s conception of mental models, human survival and its relationship to how humans come to know the world is how his own work on the nervous system led him in much the same direction as later biological thinkers such as Dawkins and Daniel Dennett, albeit with more significantly Kantian undertones. For this reason, if nothing else, Young stands out as one of the earlier biological philosophers who would later cause such academic turmoil in the eighties and nineties, and hence provides further opportunities for the historian or philosopher of science to delve into the structure and consequences of his thought. Personally, I think he surpasses both of these other thinkers in the depth of his reasoning, particularly Dawkins, who tends to present a very shallow view of nature, masked by an only-half felt sense of Darwinian wonder.

Ultimately, it has been worthwhile to present the core of Young’s biological philosophy of models and cognition, for in doing so we can see how his understanding of the organism as a homeostat led to the primacy of models in his thinking. The evolutionary demand that environmental inputs be represented, or modeled, through the homeostat’s outputs helps to account for the development of complex nervous systems. It further demands an approach to perception as an active process of searching for key features of our environment, rather than a passive reception of the entirety of the world. Another benefit of Young’s approach is that it demonstrates the reciprocity of the evolutionary development of the nervous system, and the subsequent use of that system in individual learning, allowing both to be understood in relationship to the other. The evolutionary origins of learning through models further serves to throw doubt upon the possibility of an unmediated relationship with reality through a line of reasoning much similar to that of Kant, and physiological Neo-Kantians such as Helmholtz. It is a debt that is hinted at in Young’s writing, but never explicitly stated or developed. Realizing this connection helps to clarify his belief in an underlying reality despite the highly mediated nature of perception.

Aside from the conclusions he himself draws in his consideration of models, if taken a step further to the process whereby human researchers consciously develop their own models of some feature of nature, there is the concern that what they subsequently produce will necessarily be twice removed from any absolute “target system”. All that can be said for certain about the results of the researcher’s model is whether or not it seems to work. Explanation, or indeed knowledge itself, if seen in its place along the continuum of biological nature through which evolution hit upon the human nervous system can not help but be bent towards some kind of survival or reproduction, “what works”. However, what is meant by this “advanced” survival of the human homeostat is open to discussion, and may very well be most fruitfully seen alongside the memetic theories of the last thirty years.

Young saw his work on biology, models and cognition as having definite value to philosophy, and wrote with this in mind. It is a value which has not yet been fully recognized, though, as we have now seen, it is one that must warrant further study and consideration as the tide of academic opinion turns towards an alternative view of models and memetics more in keeping with what Young had in mind long before it became fashionable.

For More Information:

Craver, C.F. “When Mechanistic Models Explain” in Synthese: An International Journal

for Epistemology, Methodology and Philosophy of Science, (2006). Vol. 153 (3), 355-376.

Dawkins, Richard. The Selfish Gene. Oxford University Press; Oxford, 1976.

Thomas, P.K. “John Zachary Young, F.R.S., Hon. F.B.A., M.A. (1907–1997)” in Journal

of Anatomy (1998). Vol. 192. 313-314.

Young, John Z. Philosophy and the Brain. Oxford University Press; Oxford, 1987.

—. What Squids and Octopuses Tell Us About Brains and Memories. The American

Museum of Natural History; New York, 1977.

—. A Model of the Brain. The Clarendon Press; Oxford, 1964.

—. Doubt and Certainty in Science: A Biologist’s Reflections on the Brain. The

Clarendon Press; Oxford, 1950.




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