poem celebrates the prodigious memory of the village parson (Goldsmith,
1770). But the greater stores of information displayed by savants appear
to have similar cranial confinements (Hamilton, 1859; Luria, 1968). On
the assumption that parsons and savants store their information
similarly, then theories of storage cannot exclude the high bar set by
the latter. Such theories have ancient roots (Murray, 1988; Draaisma,
2000). While in their 1858 Linnaean Society addresses Charles Darwin and
Alfred Wallace agreed on the power of natural selection, the latter came
to draw the line at the human brain and favored explanations that
pointed to ‘an unseen universe’ (Wallace, 1889). Not so Ewald Hering
(1834-1918), Théodule Ribot (1839-1916), and Samuel Butler (1835-1902).
In the 1870s they explicitly equated brain memory and heredity (Schacter,
1982; Forsdyke, 2006a, b; Cock and Forsdyke, 2008). ‘Heredity … is a
specific memory: it is to the species what memory is to the
individual,’ wrote Ribot (1875), but went no further. Hering invoked
molecular vibrations. Butler
(1880) was cautious:
am not committed to the vibration theory of memory, though
inclined to accept it on a primâ
facie view. All I am committed to is, that if memory is due
to the persistence of vibrations, so is heredity; and if memory
is not so due, then no more is heredity.
the twentieth century DNA was seen to localize hereditary information to
the cell nucleus, but ablation studies in rodents and primates by
neurophysiologist Karl Lashley (1960) failed to locate brain memory (‘engrams’):
engram of a new association, far from consisting of a single
bond or neuron connection, is probably a reorganization of a
vast system of associations involving the interrelations of
hundred of thousands or millions of neurons. … The conclusion
is … supported by electrical studies, that all the cells of
the brain are constantly active and are participating, by a sort
of algebraic summation in every activity. There are no special
cells reserved for special memories.
was consistent with long term memory being based on structural changes
in the synapses that interconnect neurons (‘synaptic plasticity;’
Hebb, 1949). The possibility of DNA as a neural memory store was
considered by Francis Crick (1984), but he veered towards a network
(‘connectionist’) viewpoint (Crick and Mitchison, 1995). In the
twenty-first century the Hebbian network hypothesis came under attack
and attention returned to storage of specific items of mental
information as DNA (Dietrich and Been, 2001; Arshavsky, 2006a). Could Butler
have been right? If so, then in a discipline ‘marked by exceptional
fractionation and disunity’ could Butler’s work, like that of his
famous contemporary Gregor Mendel, now be construed as a ‘missed
signal’ (Murray, Kilgour and Wasylkiw, 2000)?
major reason for ‘fractionation and disunity’ is that, unlike most
other body organs, the functions of the brain – especially its
appearance of storing information for long periods – are poorly
understood. The best remedy for disunity based on poor understanding is
‘to go back to square one’ – namely, to review the history. To
fully appreciate Butler’s contribution, it needs to be set in the context of both prior and
recent contributions to the field. Accordingly, I here begin with
terminology and describe the approaches through which we have
successfully elucidated the storage of hereditary information (genome
considering the possibility that both the synaptic plasticity and DNA
hypotheses are incorrect, I then turn to various mysterious
alternatives. Long term memory, be it chemical (e.g. an ordered sequence
of units; i.e. digital information) or physical (e.g. vibrations; i.e.
analog information), could be stored in the brain in some class of
macromolecule other than DNA, or in some unknown sub-molecular form. In
the absence of evidence for this, the brain ‘cupboard’ could be
deemed bare. Discounting the dualistic view that brain memories are
‘psychical,’ existing in neither chemical nor physical forms (Bergson,
1911; Arshavsky, 2006b), some unknown form external
to the nervous system then comes into contention. Thus, I conclude by
considering attempts to quantify the information held within the human
brain, and by reviewing modern aspects of Avicenna’s view that the
brain is a perceptual, rather than a storage, organ.
2. Terminology in
long term memory research
a recent survey, leaders in the ‘science of memory,’ while seeking
to classify types of memory, were agnostic regarding the way or ways we
store the information that makes memory possible. Instead, as in
genetics a century earlier (see below), there was much debate on
terminology (Tulving, 2007):
frequently used term is ‘representation,’ another is
‘coding.’ … Other well-known terms are ‘engram,’
‘memory image’ and ‘memory trace.’ Each has its own
connotations that vary from context to context and even from
writer to writer, although the concept lying behind all these
terms has been and continues to be relatively unambiguous.
(2007) thought failure to retrieve could be because ‘the ink has
completely faded’ rather than because of a failure of the retrieval
process itself. He concluded that ‘once memory molecules responsible
for persistence are identified, the investigation of persistence can be
put on a solid footing.’ Morris (2007) noted that listing the
‘neuropsychological attributes of different types of memory’ did
‘not satisfy the molecular neuroscientist who might assert that we
will not properly understand memory – any type of memory – until we
know the molecules and the cell-biological mechanisms that mediate
it.’ Dudai (2007) observed: ‘The question of how information is
coded and represented in brain and cognition is considered by many as
the most crucial problem in the neurosciences.’ However, with some
hand-waving, Moscovitch (2007) declared that memory should not be
considered as ‘a free-standing entity,’ but as ‘the product of a
process of recovery (an act of memory) rather than an entity which
exists independently of that process.’
our concern is long-term memory, in the present context ‘memory’
will be defined as ‘stored information’ – an object
in the sense that the hard-drive of a computer is held to be a stable
repository (Forsdyke, 2006b). The physiological process
by which we retrieve stored information is commonly referred to as
‘memory,’ but due regard to context should avoid confusion. While we
may refer to information retrieved from short or long term memories as
‘the memory’ or ‘the working memory’ of a fact or event, under
our definition retrieved information is just that – retrieved
information – it is not stored information. In the same sense,
information moving along a wire is not stored by the wire (see below).
stored information relating to a fact or event is retrieved/used by a
person, we say that the person has ‘remembered,’ or has ‘displayed
memory of,’ that fact or event. It does not follow that initially the
information was accurately and completely produced/acquired for
deposition in the store, or that the retrieved information was an
accurate and complete copy of the stored information, or that the
retrieved information took the same form as either the initially
produced or stored forms. Thus, a hard-drive stores information as
binary digits (bits) and its retrieval involves numerous transformations
leading to display on a monitor. Under our definition, memory is
unconscious. Information is retrieved from unconscious memory and it is
either made conscious (i.e. a fact or event is recalled and may then
influence some action), or it remains unconscious (i.e. we can know of
its recall only if it influences some observed action of a type we would
deem ‘automatic’ or ‘instinctual’).
the extent that a wire can transmit information it, albeit momentarily,
acts as a store for that information (Treves, 2007). However, the ‘store’ concept implies a time delay where
information deposited at a site (through an act of transmission) is
preserved at that site until a time when it may be retrieved (through an
act of transmission). Since information can accumulate in a store then,
for short transmission distances, the dimensions of the store could be
greater than those of the wire. The act of deposition implies that there
is a signal source (ultimately an information producer from which the
information was acquired) and that the store is open and has sufficient
space. The act of retrieval implies that the store is open and contains
the information, and that there is a signal recipient (and hence a
potential information user).
nature and arrangement of the information in the store may influence the
nature of future transmissions (acquisitions/retrievals) to/from the
store, either by external agencies (e.g. a questioning teacher) or by
the individual store owner (e.g. a student). For example, one’s
knowledge influences one’s perception of one’s environment
(selective attention). The fact that cues can facilitate retrieval (Forsdyke,
1978), suggests that often the factor limiting retrieval is the
retrieval process itself, rather than presence in the store.
bioinformatics as heuristic
we come to understand the informational aspects of one bioscience may be
of heuristic value when we seek to understand informational aspects of
another bioscience. Thus, irrespective of whether DNA is the basis of
long-term brain memory, consideration of the research approaches through
which we have, with spectacular success, come to understand the
production/acquisition, storage, and retrieval/use of genomic
information, may provide a guide to the approaches through which we may,
in the future, come to understand the same triad with respect to brain
information (Hamilton, 1859).
today may be in the same situation as genetics a century earlier.
Abstract ‘factors’ or ‘character units’ (for which the name
‘gene’ was emerging) appeared to provide an informational basis for
disparate phenomena. But being fully occupied describing such phenomena
– associated with the production (by replication and variation) and
retrieval (leading to phenotypic expression) of information in genes
(the genotype) – the early geneticists were not overly worried about
their material form (Forsdyke, 2001, 2006b; Cock and Forsdyke, 2008).
Yet one geneticist recognized a need for ‘a knowledge of the chemistry
of life far higher than that to which science has yet attained,’ and
foresaw ‘it may well be that before any solution is attained, our
knowledge of the nature of unorganized matter must first be increased.
For a long time yet we may have to halt’ (Bateson, 1913). Indeed, only
after the characterization of DNA forty years later (Watson and Crick,
1953) did there emerge a true understanding of the production (by
replication and mutation) and retrieval (by transcription) of hereditary
genetic memory store was sufficiently stable to permit the information
encoded within DNA to persist during an individual lifetime and through
successive generations. Yet, regarding information production, DNA
retained sufficient plasticity to allow mutations and the encoding of
new genes. Regarding information retrieval, DNA stored in a distinct
location (the cell nucleus) served as a template (master memory) from
which ephemeral copies (messenger RNAs as ‘working memory’) could be
dispatched (transcribed) often in response to specific recall signals.
The information in messenger RNAs could then be translated as amino acid
sequences (proteins), so giving expression to the corresponding
phenotype. The cell (and hence the individual) containing the DNA could
be seen as responding to the signals by expressing the recalled
information in an adaptive manner. Thus, information in the nuclear
store (genotype) could be retrieved, used, and then observed as
phenotype. Knowledge of the chemical nature and location of the store
facilitated the ablation of specific genes, the phenotypic consequences
of which could then be observed. Unlike brain memory, where ‘the only
proof of there being retention is that recall actually takes place’
(James, 1890), the student of heredity could directly work on DNA memory
and was no longer confined to observing input and output from an
abstract postulate (Capecchi, 2001).
sometimes ablation of segments of DNA produced no observable result –
an indication of latency. We have long known from classical Mendelian
studies that information can remain latent in DNA, perhaps for many
generations. Some DNA information can exist independently of its recall.
It does not require validation by frequent recall. If and when it
occurs, the recall process can sometimes change the information (e.g. by
exchanging base units; Mattick and Mehler, 2008). Genetic information
when expressed can be less (or more) than the genetic information
existing in DNA. Indeed, sometimes recall (transcription) of DNA
information can change the master template itself (Beletskii and Bhagwat,
1996). Thus, the processes of acquisition, storage and retrieval of
genetic memories are interdependent to a greater extent than might
appear from their sequential order.
4. Brain memory
and heredity equated
millennia people have questioned, not that memory is located in the
brain, but what form it can take in the brain. Through introspection and
observation of others, many facts of memory were as apparent to our
ancestors as to us today (Martino, 2007). The Swiss naturalist Charles
Bonnet (1776) noted:
this memory is connected with the body, it must depend upon some
change which must happen to the primitive state of the sensible
fibres by the action of objects. I have, therefore, admitted as
probable that the state of the fibres on which an object has
acted is not precisely the same after this action as it was
before. I have conjectured that the sensible fibres experienced
more or less durable modifications, which constitute the physics
of memory and recollection.
notion that hereditary information and mental information were stored in
the same form occurred independently to Hering, a professor of
Prague, and to Butler
(Cock and Forsdyke, 2008). However, whereas Hering (1870) published only
one essay – ‘On memory as a universal function of organized
matter,’ – Butler developed the theme in numerous books and papers,
beginning with his novel Erewhon
in 1872 and terminating, in exasperation, in the 1890s (Jones, 1919).
Previously I discussed their work with a focus on heredity (Forsdyke,
2006a). The present paper considers mental aspects.
our inability to go ‘behind the scenes’ and directly observe memory,
Hering lamented that the ‘threads’ of unconscious life could only be
perceived if they became conscious (Butler, 1880):
was conscious of this or that yesterday, and am again conscious
of it today. Where has it been in the meanwhile? It does not
remain continuously within my consciousness, nevertheless it
returns after having quitted it. Our ideas tread but for a
moment upon the stage of consciousness, and then go back again
behind the scenes, to make way for others in their place. As the
player is only a king when he is on the stage, so they too exist
as ideas so long only as they are recognized. How do they live
when they are off the stage? For we know that they are living
somewhere; give them their cue and they reappear immediately.
They do not exist continuously as ideas; what is continuous is
the special disposition of the nerve substance in virtue of
which this substance gives out today the same sound which it
gave yesterday if it is rightly struck. … Between the ‘me’
of today and the ‘me’ of yesterday lie night and sleep,
abysses of the unconscious; nor is there any bridge but memory
with which to span them. Who can hope after this to disentangle
the infinite intricacy of our inner life? For we can only follow
its threads so far as they have strayed over within the bounds
drew parallels between unconscious inborn behavior (e.g. a new born
chick knowing instinctively how to run and peck), and unconscious
learned behavior (e.g. the automatic replaying of a musical composition
by a professional pianist). They proposed that (1) both types of
unconscious activity had the same stored informational base and, for
economy of hypothesis, (2) actions, ideas and facts that became
conscious would also derive from this common base.
not committed to vibration ideas,
explored possible mechanisms by which vibrations might interact to allow
associations and recall (Butler, 1880):
this memory remains for long periods together latent and without
effect, it is because the undulations of the molecular substance
of the body which are its supposed explanation are during these
periods too feeble to generate action, until they are augmented
in force through an accession of suitable undulations issuing
from external objects; or, in other words, until recollection is
stimulated by a return of the associated ideas. On this the
internal agitation becomes so much enhanced, that equilibrium is
visibly disturbed, and the action ensues which is proper to the
vibration of the particular substance under the particular
words can be compared with those of a modern neurophysiologist (Pribram,
1991): ‘Brain processes undergo a dynamic matching procedure until
there is a correspondence between the brain’s microprocesses and those
in the sensory input. … We consider brain processes to resonate to the
patterns that stimulate the senses.’ Similarly, information scientist
Pieter van Heerden (1968) considered that: ‘Intelligence amounts
simply to matching the incoming information with a huge reservoir of
stored information. This matching has to be carried out physically, bit
by bit, in space and time.’ Butler (1880) was also concerned with matching when correspondences were not
the memory … were absolutely perfect; if the vibration
(according to Professor Hering) on each repetition existed in
its full original strength and without having been interfered
with by any other vibration; and if, again, the new wave running
into it from exterior objects on each repetition of the action
were absolutely identical in character with the wave that ran in
upon the last occasion, then there would be no change in the
action and no modification or improvement could take place. …
On any repetition, however, the circumstances, external or
internal, or both, never are absolutely identical; there is some
slight variation in each individual case, and some part of this
variation is remembered, with approbation or disapprobation as
the case may be. The fact, therefore, that on each repetition of
the action there is one memory more than on the last but one,
and that this memory is slightly different from its predecessor,
is seen to be an inherent and, ex
hypothesi, necessarily disturbing factor in all habitual
action. … This is the key to accumulation of improvement … .
The memory does not complete a true circle, but is, as it were,
a spiral slightly divergent therefrom.
Butler and Semon
lives of generations of
Butlers, Darwins and Batesons overlapped through their common schooling (
University). At Cambridge Butler studied mathematics and classics and gained a
first class degree in the classical tripos of 1858. The following year
he sailed to New Zealand
with the leading biochemistry textbook of his time – Justus von
Liebig’s Agricultural Chemistry. Shortly thereafter he acquired a copy of
Charles Darwin’s The Origin of
Species as, back in
Europe, did Gregor Mendel who was quietly founding the science of genetics.
While Mendel was breeding peas and reading
was breeding sheep and reading
in New Zealand. His correspondence with his father, a clergyman with an interest in
botany, reveals a keen eye for geology and for new plants and animals (Butler, 1863). Hoping to achieve financial independence,
set out to make, not just a living, but a small fortune. This focused
his mind powerfully on the task of keeping his flocks healthy and
reproductive. His first articles on evolution were published in
and soon received
’s commendation. In 1864
returned to a life of art and scholarship in
London, where he resided with his cat only a short walk from the British
Museum Library, and twice visited
at his house in Kent (Cock and Forsdyke, 2008).
his first major book on evolution, Life
expressed his debt to the philosopher Ribot in Paris (Butler, 1878), but he had been unaware of Hering’s essay, which he was later
quick to acknowledge. The fact that
had independently achieved the same synthesis as one of
Europe’s leading neurophysiologists attests to the depth of his reading and
the penetrance of his thought. However, the book’s modest introduction
gave ammunition to those who might later disparage it on account of the
author’s lack of formal education in biology: ‘My aim is simply to
entertain and interest the numerous class of people who, like myself,
know nothing of science, but who enjoy speculating and reflecting (not
too deeply) upon the phenomena around them.’ Wallace (1879) reviewed
the book positively advising ‘careful consideration to the views of a
writer who, although professedly ignorant of all science, yet possesses
“scientific imagination” and logical consistency to a degree rarely
found among scientific men.’ Furthermore, beneath the ‘sparkling
surface there is … much solid matter, and though we can at present
only consider the work as a most ingenious and paradoxical speculation,
it may yet afford a clue to some of the deepest mysteries of the organic
world.’ Although Butler is not named, a hint at the furor wrought among those around Charles
Darwin (‘Grampus’) is provided by the novelist George Eliot (1879)
in her Impressions of Theophrastus
Such. Yet, with hindsight, Butler’s alleged superficial knowledge of the literature of science appears
of little consequence when compared with the Darwinians’ unawareness
of the contribution of Mendel (1866) to that literature.
Butler’s third evolution book, Unconscious
Memory (1880), received severe criticism from
Darwin’s research associate, the neurophysiologist George Romanes
(1848-1894). Bewildered ‘at the vanity which has induced so incapable
and ill-informed a man gravely to pose before the world as a
was given three pages in Nature
(1881) to vent his discontent:
this view … is interesting if advanced merely as an
illustration; but to imagine that it reveals any truth of
profound significance, or that it can possibly be fraught with
any benefit to science, is simply absurd. The most cursory
thought is enough to show that, whether we call heredity
unconscious memory, or [call] memory of past states of
consciousness the hereditary offspring of those states, we have
added nothing to our previous knowledge either of heredity or of
Butler’s reply was initially stonewalled by the editor – a friend of
Romanes (Forsdyke, 2004). It required a letter to the publisher,
Macmillan, threatening legal action, to secure publication (Jones,
1919). While criticizing with one hand, Romanes appeared to be adopting
Butler’s ideas without acknowledgement with the other (Butler, 1890). Indeed, Romanes was taken to task in The
Athenaeum (Anonymous, 1884) for not having the “literary
courtesy” to cite Butler
(Romanes, 1884a). This was brushed off by Romanes (1884b):
can be no memory in a seed or in an egg, and therefore when we
say that a plant grows out of a seed, or an animal grows out of
the egg, because they each remember to have done the same thing
many times before and thus know how to do it again, we are
merely restating the observed facts of heredity in metaphorical
terms. With just as much, or as little, meaning we might
attribute the observed facts of chemical affinity to the sundry
elements falling in love with one another. Of course I should
have no objection … if it were represented to be what, in
fact, it is – a metaphorical or poetic rendering of observed
phenomena. My objection begins when I find that he lays claim to
furnish a scientific explanation of the phenomena of heredity by
any such means.
followed a heated debate enjoined by the zoologist E. Ray Lankester and
the philosopher Herbert Spencer. A literal interpretation of Butler’s
argument, namely the possibility that each cell of a body might contain
a memory (stored information) in the form of a linear text (now known as
DNA) that could specify the individual characters and development of the
organism, was quite beyond the conceptual framework of Romanes and his
over a decade
fought back claiming he was writing for ‘future students of the
literature of descent’ rather than for ‘my immediate public’ (Butler, 1887). He then moved on to more congenial pursuits. However, direct
but qualified support came from Marcus Hartog, Professor of Zoology in
and, less conspicuously, from
Darwin’s son Francis (Cock and Forsdyke, 2008). From America
came indirect support through praise of Hering alone (Cope, 1882). In a
discussion of heredity (which he called ‘genesiology’), Alpheus
Hyatt (1893) referred positively to Hering’s ‘mnemonic theory,’
or the ‘theory of mnemogenesis.’
years after Butler’s death in 1902, the German biologist Richard Semon
(1859-1918) in his Die Mneme
revived the ideas of Hering and Butler, even to the extent of their
proposal that some of the brain memory of a parent would be passed
through the germ-line to its offspring (Lamarckism; Forsdyke, 2006a).
Hering and Butler were acknowledged, but Butler’s ‘brilliant’
ideas were considered to be ‘mixed with so much questionable matter,
that the whole, compared with Hering’s paper on the same subject, is
rather a retrogression than an advance.’ The latter quotation is from
an English translation (Semon, 1921) made between 1912 and 1914 with
input from Semon, whose unbridled Lamarckism was backed by numerous
references to experiments later found to be in error or fraudulent –
the studies in Oslo of F. C. Schübeler, in Chicago of William Tower,
and in Vienna of Paul Kammerer (with whom Semon frequently corresponded;
Schacter, 2001). Regarding ‘the famous case of Schübeler’s wheat,’ William Bateson (1913) considered that ‘without careful
simultaneous control experiments this evidence is almost worthless,’
and was ‘surprised that Semon should claim these experiments as one of
the chief supports for his views.’ It is likely that Bateson discussed
such experiments with Nikolai Vavilov
when he visited England in
1913, and the criticism may have been a factor in Kammerer’s suicide
in 1926 (Cock and Forsdyke, 2008). Years later, claiming successful
transmission of the early maturing (vernalized) state to wheat offspring, Trofim
Lysenko, with Stalin’s help, sent Vavilov and other Russian
geneticists to early graves (Cock and Forsdyke, 2008).
was not essential that Lamarckism be correct for there to be a
fundamental equation between the two storage forms for heredity and for
brain memory (dubbed ‘engrams’ by Semon). Lamarkism was concerned
with the manner of the transmission of hereditary information, not with
its form. Nevertheless,
Semon’s work was much criticized (Schacter, 1982). A bright spot was
the 1908 Presidential Address to the British Association where Semon was
warmly praised by Francis Darwin who ‘expressed my indebtness to this
work, as well as for the suggestions and criticisms which I owe to
Professor Semon personally.’ A second book, Die mnemischen Empfindungen, published in 1909, was translated as Mnemic
Psychology with an introduction by Vernon Lee (Semon 1923). She
noted that Semon had ‘advocated the views concerning Memory and
Heredity with which many of us English lay readers are familiar, thanks
to the literary genius and incomparably challenging personality of
1918, amidst war-end anarchy, Semon’s wife died of cancer and Semon
committed suicide. Since many in Germany
at that time suffered equally deeply, his biographer doubted whether the
‘psychological roots of Semon’s demise’ could be ‘unambiguously
specified’ (Schacter, 1982). As with Kammerer, the criticism of his
work may have been a factor. In an introduction to a reprinting of Unconscious
Memory, Hartog (1910) had examined Semon’s above-quoted
‘judgement’ on Butler, noting that: ‘Since Semon’s extended
treatment of the phenomena of crosses might almost be regarded as the
rewriting of the corresponding section of “Life and Habit” in the
“Mneme” terminology, we may infer that this view of the question was
one of Butler’s “brilliant” ideas.’ Semon having cited Butler, albeit only once, there was no question of plagiarism. Nevertheless,
in his article ‘Samuel Butler and recent mnemonic theories,’ Hartog
(1914) pointed out that Semon’s few references to Hering and Butler in
Die Mneme barely reflected his
debt to those authors. Comparing Life
and Habit with Die Mneme, paragraph by paragraph, Hartog noted that ‘the
confluence of his [Semon’s] thought with Butler’s is at this point absolute, and the same holds good for a great part
of Die Mneme.’ The date is
ominous. With war-time restrictions on scientific communication (Cock
and Forsdyke, 2008), it is possible that Semon did not learn of the
criticism until 1918.
from his word ‘engram,’ Semon might have sunk from view had it not
been for a paper noting that
his ‘rich theoretical constructs and novel conceptualizations’ had
been praised by many leading figures, including the philosopher Bertrand
Russell and the physicist Erwin Schrödinger (Schacter, Eich and Tulving,
1978). Although there was mention of the early work of
(1859), the paper confined its historical context to the period
1885-1935 and there was no mention of Hering or Butler. This omission was corrected in a later book, but the correction was
primarily to disparage.
was labeled ‘a classical crank’ in the same category as Lysenko (Schacter,
1982). Despite a reprinting of the book, without amendment save for a
new title (Schacter, 2001; Murray, 2002), Semon’s terms ‘engraphy’
(acquisition), ‘ecphory’ (activation for retrieval) and
‘homophony’ (a development of the
resonance ideas of Butler), have not been widely adopted.
6. Savants and
the distinction between labile short term memory (disruptable by trauma
or electric shock) and stable long term memory has been relatively clear
(Ribot, 1882; Dudai, 2004), in a review of a century’s progress
McGaugh (2000) acknowledged that ‘despite theoretical conjectures’
little is known of the processes by which information relating to human long term memory is
consolidated for storage. Not so readily acknowledged was the fact that
our knowledge of the location
of the store was equally deficient. The reason is not difficult to
discern. In general, when contemplating potential storage sites for an
object, we take into account whether it is likely to be needed at short
notice, its size, stability, and potential compressibility. We know that
human long term memory can be stable and is often accessible at short
notice, but fitting it into the cranial ‘suitcase’ faces the twin
problems that we know neither what form (or forms) it can take, nor its
magnitude, save that it is very great and, in savants, amazingly so.
magnitude, as a rough yardstick we can take DNA with its four base
‘letters’ (the purines A and G, and the pyrimidines C and T). Making
the simplifying assumption that each letter is equally probable in a DNA
sequence, then two ‘yes/no’ decisions are required to assign a
letter. Is the letter a purine? If no, it must be a pyrimidine. If yes,
is it A? If not, it must be G. Information scientists then say that each
letter is ‘worth’ two ‘bits’ (binary digits) of information. By
this measure, the information content of a haploid human genome (3 x 109
bases) is 6 x 109 bits. This is similar to the information
capacity of a standard 12 cm diameter compact disk (700 megabytes = 5.6
x 109 bits). Normally two haploid DNA copies (of paternal and
maternal origin) are confined within the nuclear membrane of a cell (12
x 109 bits; Forsdyke, 2006b).
from his other memories, a savant described by Treffert and Christensen
(2005) was able to recall 9000 books. If each book had 100 pages each
containing 1000 letters then, making the simplifying assumption that
each letter is equally probable and, being drawn from a 26 letter
alphabet, is worth 5 bits, his memory for books is at least 4.5 x 109
bits. Thus, the DNA of just one
cell, if it had no other functions, would be sufficient to encode this.
From various assumptions, von Neumann (1979) estimated a lifetime
accumulation of 2.8 x 1020 bits which, from the above
assumptions, could be held in 2.3 x 1010 cells. Assuming 5 x
105 cells per cc of brain (Heller and Elliott, 1954), this
would require a brain volume of 5 x 104 cc (i.e. the volume
of a cube with 37 cm sides). Discounting the amount of detail involved
in the storage of pictorial information, Landauer (1986) arrived at an
estimate considerably lower than that of von Neumann. However, a recent
study concludes that “visual long-term memory has a massive storage
capacity for object details” (Brady et al., 2008). Given the
uncertainty of the assumptions, the idea of cranial DNA storage of long
term memory would seem not too far out. If so, one might expect to find
either quantitative or qualitative differences between the DNAs of brain
cells and cells of other tissues. Furthermore, species with large brain
memories would have more DNA in their brain cells than species with
small brain memories.
brain is the organ par excellence that defines the human animal. Yet human
brain cells have the same quantity of DNA as other cells of the human
body and, indeed, as the cells of mammals in general (which includes
rodents and other primates; Heller and Elliott, 1954; Leslie, 1955).
Conventional genes make up less than 2% of DNA and the remaining 98%,
sometimes dismissed as “junk,” likely serves functions other than
brain memory (Forsdyke, 2006b). It is now technically feasible to
qualitatively compare DNAs of individual brain cells from different
parts of a fresh post-mortem human brain. From the above, the
presumption is that differences of an order sufficient to account for
individual memories will not be found (Kaminsky et al., 2005).
as in some written languages certain letters are given accents to guide
pronunciation, DNA can be modified by the addition of chemical groups (methylation)
to base units. Whether this would account for long term memory remains
to be determined (Holliday, 1999; Arshavsky, 2006a). There are various
observations that warrant further study. For example, in brain cells an
unknown chromogenic substance can interfere with the quantitation of DNA
(Heller and Elliott, 1954). But, on balance, current evidence indicates
that, regarding memory, the brain’s DNA ‘cupboard’ is bare. This
raises the question of non-DNA alternatives. Broadly, this category
includes other polymers (RNA, protein, lipid, carbohydrate; Mercer et
al., 2008; Routtenberg, 2008) or submolecular forms perhaps related to
“quantum computing” (Venema, 2008). Also in this category is the
idea of the brain as a three dimensional holographic storage network (Heerden,
1963; Pribram, 1971).
all these alternatives the thinking is conventional in that long term
memory is held to be within the
brain. The unconventional alternatives are that the repository is
either elsewhere within the body, or extra-corporeal. The former is
unlikely since the functions of other body organs are well understood.
Remarkably, the latter has long been on the table (Avicenna, 1631).
Since it requires ad hoc postulates for which there is barely a shred of evidence, we
should first prepare the ground.
7. Internal signal
detection and emission
are surrounded by moving forms of energy/mass (wave/particles), some of
which we can detect biologically (e.g. photons), some of which react
only weakly if at all with cells (Maeda
et al., 2008),
and some of which, as far as we know, are not detected biologically (Wilczek
and Devine, 1987). Even instruments detect some forms only with
difficulty (e.g. neutrinos). Other postulated forms are either
undetectable, or their detectability is much debated (Bernabei et al.,
first life forms to evolve (the “replicators”; Dawkins, 1976)
probably did not detect photons. They existed in a sea of photons but
were blind to them. At some point, through mutation, some molecules
within a life form happened to acquire the ability to respond to
photons. Through natural selection that organism prospered and its
descendents further evolved their photon-detection abilities so that
today we see organisms with external organs (eyes) specialized for this
task. Likewise, we see ears specialized for sound waves.
some extent, the size of an organ reflects the importance of the
corresponding modality for survival. But wave/particle detection does
not necessarily correlate with an external organ. A wide variety of
species, including mammals and birds, orientate using the earth’s weak
magnetic field, a process that may depend on the sensitivity of free
radical reactions to magnetic influence (‘chemical magnetoreception;’
Maeda et al., 2008). Also, certain ‘magnetotactic’ bacteria can
concentrate particles of iron oxide – minicompasses – within
themselves (Frankel and Blackmore, 1989). With magnetic fields there is
little delay between detection and an interpretation that leads to an
adaptive response. Furthermore, since the signal is not impeded by
biological tissues, receptors can be located internally.
principle, an organism that can receive a signal from its environment
has the potential to evolve to transmit that type of signal to its
environment. A firefly detects photons with its eyes, but it can also
transmit photons to external eyes, which include our eyes. The photons
are meant to attract another individual of the same species of the
opposite sex. Males and females of a given firefly species
intercommunicate by means of specific movements as they emit light
(Lewis and Cratsley, 2008). Hence a firefly of one species will not
attempt to mate with a firefly of another species. There is
discrimination between individuals within a species in that an
individual emitting stronger signals will be preferred. However, a
firefly cannot focus its signal on a particular individual. From this we
can conclude that, (1) if at some point in time, it became of adaptive
advantage to an organism to detect a form of wave/particle, and (2) if
such detection were within the realm of physical possibility, and (3) if
the appropriate mutations occurred, then we might later find in its
descendents an external or
internal structure that would mediate such detection. Furthermore,
the organism, by virtue of the same or a different structure, might act
as a source of the same form of wave/particle, which might be
transmitted with some degree of specificity to a given target.
8. Brain as a
transmission of linguistic information between early hominoids, first
orally and then in written form, is regarded as a major evolutionary
event (Noll, 2003). To corporeal transmission from generation to
generation through heredity was added extra-corporeal transmission
through language written on some medium permitting long-term storage
either locally or at a remote site (Romanes, 1895). In the twentieth
century, to writings preserved on stone and paper were added recordings
on computer hard-drives (Draaisma, 2000). Computer scientist John
McCarthy (1972) noted there was no intrinsic need for a hard-drive to be
near the computer it served. With the advent of the internet this has
become a reality. Local data storage needs can be low. Instead, files
are saved to, and accessed at, a remote location (e.g. the ‘cloud
computing’ offered by Amazon Corporation).
this example in mind, it is easy to imagine that a biological system –
a brain – might store information similarly. We can think of a brain
as both a perceptual, and a transmitting, organ. There would need to be
a two-way transaction, from the brain to the extra-corporeal information
store, and back from that store to the brain’s ‘retina.’ There
would have to be an appropriate form of ‘thought ray’ that would
vastly exceed the speed of light. Furthermore, one would transmit and
‘see’ with one’s brain only personal messages. Incredible though
this may seem (see next section), such a scheme, based on the idea of
the universe as a holographic information storage device and the
principle of “non-locality” (Bohm, 1981) has been given ‘a
possible “hardware” implementation’ by computer scientist Simon
Berkowitz (1993), and cited with approval by a leading neurophysiologist
consolidation’ of brain information, dependent on protein
synthesis, occurs in a few hours (short-term memory) and involves the
expression of various genes (including those encoding regulators of
G-proteins and transcription factors; Fordyce et al., 1994; Ingi et al.,
1998). These genes are also involved in signal reception by non-neural
cells (Siderovski et al., 1990), so are
not brain-specific. For long-term memory, later (or in parallel) ‘system consolidation,’ independent of protein synthesis, takes
weeks or months for completion (Dudai, 2004). The latter would
correspond to the period of transmission of information to the
postulated remote store. In that recall would appear to be almost
instantaneous, under this hypothesis the brain’s power as a perceptual
organ would appear even more amazing than its power as a transmitter.
(2007) sees the brain as a receptor/transmitter of a form of
wave/particle for which no obvious external structure would be needed.
For example, consider ‘dark matter particles.’ Much of the mass of
the ‘universe’ is dark matter that does not absorb light. Light
waves from distant parts pass through dark matter but are unaffected by
it. We know that dark matter exists because, by virtue of its great
mass, it affects the movement of visible objects. Whatever dark matter
is, it does not seem to consist of the same building blocks as visible
matter (protons, neutrons, electrons; Wilczek and Devine, 1987).
Currently it is hoped that ‘dark matter particles’ will, like
neutrinos, be detected by devices hidden deep in the earth to screen out
other signals. Indeed, using a device containing ultrapure sodium iodide
crystals, which should emit photons when struck by dark matter
particles, Bernabei et al. (2004) have claimed positive results.
of whether the putative ‘thought ray’ wave/particle does relate to
dark matter, the point is that there are wave/particles ‘out there’
that we are just beginning to understand. Paralleling the detection of
photons by a complex of coenzyme (retinol) and protein (rhodopsin), it
is quite conceivable that something akin to sodium iodide (acting as a
coenzyme) might be bound in a specific configuration by a protein
(enzyme) so as to screen out other signals and detect only one type of
wave/particle. Just as the retinol-rhodopsin system evolved, so other
systems conferring adaptive advantages could evolve. If we are to take
Wallace seriously (see Introduction), this adaptive advantage (or an
exceedingly improbably chance event) could have occurred just prior to
the emergence of Homo sapiens.
for personifying messages, one possibility would involve global position
monitoring, since each individual occupies a distinct (albeit moving)
position in time and space (O’Keefe and Burgess, 2005). Another
possibility would be a barcode labeling system (Berkovich, 2007).
Whatever the system, the stored information, wherever it may be, should
be structured in some way – i.e. it should have a syntax. Presuming
this syntax to have evolved before the evolution of our spoken language,
then the “deep structure” of this preexisting syntax might have guided the evolution of our linguistic
syntax (Chomsky, 1965). Indeed, digital language acquisition appears
late both in anthropoid evolution and in human development, seeming to
dictate a period of post-natal brain expansion and continuing
foetus-like helplessness that contrasts dramatically with the newborn
state of our nearest anthropoid relatives (Noll, 2003). Finally,
it can be noted that a possible consequence of failure to personify
accurately could be Lamarckian transmission to offspring by a path
(parent to extra-corporeal agency and back to offspring) differing from
that of classical Lamarckism (parent to germ-line to offspring). Indeed,
this line of reasoning could explain various neuropathological states
such as alleged multiple personality syndrome (Ribot, 1882).
9. Argument from
‘gazing rustics rang'd around’ the parson found it incredible that
‘one small head could carry all he knew.’ But we may be sure that
none really doubted that it did. Not so the Arabic physician Avicenna
(980-1037), who declared the brain cupboard to be bare. He ‘denied to
the human mind the conservation of its acquired knowledge’ and
explained ‘the process of recollection’ as ‘an irradiation of
divine light, through which the recovered cognition is infused into the
intellect’ (Hamilton 1859). Similarly, Murray
(1988) refers to Avicenna’s ‘agent intellect’ which ‘acted to
transmute sensory knowledge into a kind of knowledge that was not
“material” – that is, not associated with any body part.’
Perhaps Avicenna had observed that, despite the intellectual impairment
of human microcephalics, there were exceptional cases where
‘intelligence’ (to which memory must make a considerable
contribution) is normal (Teebi, Al-Awadi and White, 1987; Hennekam, van
Rhijn, and Hennekam, 1992). More likely, Avicenna was influenced by the
culture of Arabic psychological science which attempted to apply ‘the
laws of physics to the soul-body complex’ (Martino, 2007). Following
the death of a body its extra-corporeal long-term memory might persist
for some time – the physical equivalent of the term ‘soul’ (Yrjönsuuri,
2007). Thus, its ‘soul’ would not leave
a body at death since it had never been in the body in the first place.
Rather, death would leave the ‘soul’ stranded.
the notion that our mental information is stored outside the brain is even more incredible than that it be stored
inside. Our credulity is further stretched by the need for ad hoc postulates – e.g. ultrafast ‘thought rays.’ Even if we
disregard the religious baggage associated with the phrase ‘divine
light,’ the arguments of the professionals (Bohm, 1981; Berkovich,
1993), and discussions of paranormal phenomena by others (Talbot, 1991),
sound like science fiction, and are unlikely to convince the readers of
this paper. Neither do they its author. However, there may be vestiges
of truth amongst the dross that we poor creatures, imprisoned within the
first decade of the twenty-first century, can comprehend no better than
those imprisoned in the penultimate decade of the nineteenth century
could comprehend Butler.
problem is compounded by activities of the ‘intelligent design’
movement which may interpret the holographic universe idea as showing
that it was right all along. But the present paper, like its predecessor
(Forsdyke, 2006a), lends no comfort in this respect. It simply states
that we must shift our preoccupation with the biosphere to appreciate
that life evolved as the result of interactions both terrestrial and
extra-terrestrial. Our ability to respond to photons, most of which are
generated extra-terrestrially, is an obvious example. Whatever is ‘up
there’ and whatever is ‘down here,’ they coevolved
by a process that can be construed as monistic and, in its essentials,
Darwinian. This seems to be the point that anthropologist Gregory
Bateson, the atheist son of an atheist father (William), was struggling
to articulate in the 1970s (Bateson, 2008): ‘There is something that
human religions are trying to get at that matters. And they get at some
of it in many different ways which include vast amounts of nonsense,
much of it dangerous, but we perhaps do not yet have a better way of
getting at it, whatever it
to the extent that
foresaw DNA and that modern commentators invoke DNA as a memory store, Butler’s work was a ‘missed signal’ (Murray, Kilgour and
2000). However, the field is in disarray and DNA is but one of a range
of possible solutions to the memory problem. Neurophysiologist Eric
Kandel (2006) observes: ‘In the study of memory storage, we are now at
the foothills of a great mountain range. … To cross the threshold from
where we are to where we want to be, major conceptual shifts must take
place.’ Hopefully such shifts will instigate an inventory of
brain-specific macromolecules to exclude a polymeric form that,
DNA-like, might store information digitally. Before seeking exotic
storage modalities, we should ensure that the brain ‘cupboard’ is
indeed bare of forms more in keeping with current paradigms.
Furthermore, although brain information may be stored in some
sub-molecular form, or even extra-corporeally, at some point that
storage form would have to interface with more conventional
macromolecular species (e.g. proteins). Specific adaptations for this
role would distinguish them from other macromolecules.
despite the fascinating ongoing studies of input and output from brain
memory that occupy so many, it seems in William Bateson’s words that
‘for a long time yet we may have to halt.’ As things get more
complex new properties may emerge – the principle of emergent
properties. Such properties may be merely decorative (Gould, 2002), or
they may function in some novel context. When we incorporate the
universe in our evolutionary scheme (i.e. a higher level of complexity
than the terrestrial) we should recognize the possibility of the
emergence of new properties, even though we may know, neither if such an
emergence would be feasible, nor what the properties might be and what
scientific discipline might best address them. In practical terms, the
halt means a diversion of resources to allow new contributions from a
variety of disciplines. The
heuristic might guide our future studies. That which is deemed
metaphorical may not remain so. Metaphors can die and become literal (Draaisma,
2000). There will be those, like
, who will urge us to lift our eyes to new horizons (Berkovich, 1993).
While they may lack a formal training in neuroscience, we should listen
main arguments for extra-neural long-term storage of brain information
have been presented, one quantitative and one historical. 1. Human brain
size does not correlate with the quantity of information it appears to
contain. Savants do not have larger brains than normal, and
microcephalics do not necessarily have subnormal memories.
2. Charles Darwin spent much time setting out various
combinations of 26 units in linear order on paper. Yet, that each cell
of an organism might contain similar digital information, now known as
DNA, was beyond his conceptual horizon. Likewise, many today compute
using remote information storage yet are unlikely to countenance the
possibility that their own brains might functioning similarly. While
this may appear far fetched, with the emotional attack on
in mind, hopefully they will considered it objectively.
Murray reviewed the text and gave much valuable advice. Queen’s
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