THE BRAIN

THE BRAIN is wider than the sky,
For, put them side by side,
The one the other will include
With ease, and you beside.

The brain is deeper than the sea,
For, hold them, blue to blue,
The one the other will absorb,
As sponges, buckets do.

The brain is just the weight of God,
For, lift them, pound for pound,
And they will differ, if they do,
As syllable from sound.

Emily Dickinson (1830-86)

Memory studies in biological systems distinguish three informational processes that are generally sequential - production/acquisition, storage, and retrieval/use. Identification of DNA as a storage form for hereditary information accelerated progress in that field. Assuming the path of successful elucidation in one memory field (heredity) to be heuristic for elucidation in another (brain), then progress in neuroscience should accelerate when a storage form is identified.

In the nineteenth century Ewald Hering and Samuel Butler held that heredity and brain memory both involved the storage of information and that the two forms of storage were the same. Hering specified storage as 'molecular vibrations' but, while making a fuller case, Butler was less committal. In the twentieth century, the ablation studies of Karl Lashley failed to identify unique sites for storage of brain information, and Donald Hebb's 'synaptic plasticity' hypothesis of distributed storage over a neuronal network won favor. In the twenty first century this has come under attack, and the idea that brain and hereditary information are stored as DNA is advocated. Thus, albeit without attribution, Butler's idea is reinstated.

Yet, while the case is still open, the synaptic plasticity and DNA hypotheses have problems. Two broad alternatives remain on the table. Long term memory is located: (1) in the brain either in some other macromolecular form (e.g. protein, lipid), or in some sub-molecular form (e.g. quantum computing and "brain as holograph" hypotheses), or (2) outside the brain. The suggestion of the medieval physician Avicenna that the brain 'cupboard' is bare, - i.e. the brain is a perceptual, not storage, organ - is consistent with a mysterious 'universe as holograph' model. Understanding how Butler came to contribute could be heuristic for future progress in a field fraught with 'fractionation and disunity.'

Keywords.  Bioinformatics, Brain, DNA, Heredity, Holograph hypothesis, Information storage, Universe as holograph

In arguing, too, the parson own'd his skill,
For, ev'n though vanquish'd, he could argue still;
While words of learned length and thundering sound
Amazed the gazing rustics rang'd around;
And still they gaz'd, and still the wonder grew,
That one small head could carry all he knew.

1. Introduction

This 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), Theodule 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:

In 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'):

This 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)?

A 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 bioinformatics). After 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

In 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):

Lisman (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.'

Since 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).

When 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').

To 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).

The 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.

3. Genome bioinformatics as heuristic

How 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).

Neuroscience 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) information.

The 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).

However, 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

For 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:

The notion that hereditary information and mental information were stored in the same form occurred independently to Hering, a professor of physiology in 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.

Noting 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):

Hering and Butler 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.   

Although not committed to vibration ideas, Butler explored possible mechanisms by which vibrations might interact to allow associations and recall (Butler, 1880):

These 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 perfect:

5. Butler and Semon

The lives of generations of Butlers, Darwins and Batesons overlapped through their common schooling (Shrewsbury and Cambridge 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 Darwin in Moravia, Butler was breeding sheep and reading Darwin 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, Butler 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 New Zealand and soon received Darwin's commendation. In 1864 Butler 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 Darwin at his house in Kent (Cock and Forsdyke, 2008).

In his first major book on evolution, Life and Habit, Butler 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 Butler 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 philosopher,' Romanes was given three pages in Nature (1881) to vent his discontent:

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):

There 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 contemporaries.

For over a decade Butler 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 Cork 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.'

Two 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. Schubeler, in Chicago of William Tower, and in Vienna of Paul Kammerer (with whom Semon frequently corresponded; Schacter, 2001). Regarding 'the famous case of Schubeler'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).

It 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 Samuel Butler.'

In 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.

Apart 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 Schrodinger (Schacter, Eich and Tulving, 1978). Although there was mention of the early work of Hamilton (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. Butler 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 information measurement

While 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.

Regarding 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).  

Apart 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.

The 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).

Just 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).

 For 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

We 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., 2004).

The 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.

To 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.

In 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 perceptual organ

The 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).

With 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 (Pribram, 1991).

Initial, short-term 'synaptic 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.

Berkowitz (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.

Irrespective 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.

As 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 incredulity

The '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' (Yrjonsuuri, 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.

Nevertheless, 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.

The 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 is.'

10. Conclusions

Yes, to the extent that Butler foresaw DNA and that modern commentators invoke DNA as a memory store, Butler's work was a 'missed signal' (Murray, Kilgour and Wasylkiw, 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.

Thus, 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 Butler 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 Butler , 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 carefully.

11. Summary

Two 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 Butler in mind, hopefully they will considered it objectively.  

Acknowledgements

David Murray reviewed the text and gave much valuable advice. Queen's University hosts my web-pages where some of the cited articles may be found.

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As noted, much of the above appears far-fetched. Perhaps the most penetrating intellect of the second half of the 20th century, Francis Crick (1916-2004), turned to neuroscience around 1975. We can only speculate on the meaning of his remarks as noted in Olby's biography (2009):

Of Molecules and Men (1966). Concerning the "two cultures" divide of C. P. Snow: Crick wrote: 

Rickman Godlee Lecture (1968) at University College, London: 

The notebooks written around 1840 include the following comment: "To study Metaphysic, as they have always been studied appears to me to be like puzzling at Astronomy without Mechanics. -- Experience shows the problem of the mind cannot be solved by attacking the citadel itself. -- the mind is function of body. -- we must bring some stable foundation to argue from."

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