The dubious analogy of the ‘extra arm’

Time to resolve that cliffhanger I left you with yesterday – since when, incidentally, Heretic TOC’s hit rate has jumped significantly: seems a bit of controversy is good for business!
So, where was I? Ah, yes, I said a neuroscientist had agreed with Susie Orbach and myself that there was good reason for skepticism over a theory that paedophilia is caused by “crossed wiring” in the brain. An MRI scanning study by James Cantor and his team into the brains of paedophiles and others had shown that paedophiles have less “white matter”, this being interpreted as a dysfunctional deficiency.
Before going into the details, it might be an idea to point out that there are good reasons for not jumping to conclusions about “deficiency” based on measurements of gross brain anatomy. Not so long ago it was thought women must be less intelligent than men because their brains are smaller, but this is classically a field of study in which size really isn’t everything: the average brain weighs around 1.4kg. Einstein’s weighed only 1.2kg. True, he had more white matter than most, so the extent of this tissue and how it is “wired” may indeed be hugely important. I gather that white matter is basically a load of lard: fat. The fatty sheathing for the axons, or long, message-carrying, tails of the brain cells, acts as an insulator and hence helps signals whizz around at speed from one part of the brain to another.
Something like that. Anyway, the main point of interest here is not so much what white matter does as what factors might influence changes in its volume, especially whether its size and density could change in response to what our brains are exposed to in daily life. In the case of London taxi drivers, we know that a part of the brain associated with memory, the hippocampus, grows considerably when they study for “the knowledge” i.e. the detailed knowledge of the streets of London they must acquire to pass their exam and get their cabby’s licence. This is grey matter rather than white matter but, no matter, the changeability, or “plasticity”, of the brain could apply to various parts.
And now, at last, what really matters, who is this mystery neuroscientist I have recruited as an ally, and what does he say? Well, all I know – so it really is a bit mysterious – is that he works in the UK and is a highly respected blogger operating under the does-what-it-says-on-the-tin monika of Neuroskeptic. As he puts it, “A neuroscientist takes a skeptical look at his own field, and beyond.”
I emailed him in the hope of discovering whether my amateur speculations as to potential weaknesses in Cantor’s work might possibly have some substance. I was not disappointed. Here is what he wrote in reply, last month:

Hi Tom, many thanks for your email & extremely astute comments. Essentially I agree on all counts. I may well post about this because it’s pretty important: the extra arm analogy is just misleading. cheers, NS

Ah, the “extra arm analogy”!
OK, dear readers, if you want to know what that is all about, and I hope you do, you will need to settle down comfortably and give the exercise some quality thinking time. So take a break at this point, if necessary, and come back to it after.
An interesting study in this area was J.M. Cantor et al.’s sMRI paper “Cerebral white matter deficiencies in pedophilic men”. Journal of Psychiatric Research, Volume 42, Issue 3, Pages 167-183 (2008)
The study looked for brain regions that distinguish pedophilic from nonpedophilic men. Pedophiles were found to have less white matter. The authors suggested that the regions in question operate as a network for recognizing sexually relevant stimuli and that pedophilia results from a partial disconnection within that network.
The work is one of a series of papers purporting to indicate that pedophiles have brain deficiencies resulting from “perturbation” of prenatal development, and other misfortunes such as trauma from childhood head injuries. Papers have shown lower average IQ of pedophiles and far more left-handedness than average.
Leaving aside methodological problems with the IQ etc. studies, I would be interested to know whether Neuroskeptic sees any grounds for scepticism over this white matter paper. Is it just the new phrenology or something more substantial?
The thing is, the speculation offered about the said white matter “deficiencies” (Does anyone know how much white matter is sufficient?) does not appear to offer any particular explanatory model for causing paedophilia. Is there an issue here as regards direction of causation? Could paedophilia cause changes in brain anatomy, rather than the other way around?
Writing about structural MRI studies, including his own, of paedophilia, in an article aimed at non-specialists in this field, James Cantor acknowledged the question mark over direction of causation, and explained his own thinking:

When comparing pedophilic and nonpedophilic men, one must remain careful not to confuse cause with effect. That is, one must consider carefully whether the brain differences we detected cause pedophilia or whether some aspect of being pedophilic caused the brain differences. Previous research findings suggests that it is more likely for the brain differences to be causing pedophilia than for the other way around: Although it is now known that certain brain structures respond to environmental stimulation, such as the motor cortex, there is no evidence that such stimulation causes any changes in the superior fronto-occipital fasciculus or right arcuate fasciculus (the brain regions in which pedophiles and nonpedophiles differ). Moreover, the brain regions we identified are extremely large, and no previous research has ever found changes in such large regions of the brain. As an analogy, physical exercise will generally stimulate one’s muscle tissue to grow, but one would not grow an extra arm; neurological changes occur only in a very specific manner.”

The analogy of the extra arm is a vivid and plausible one, but is it really valid? At a time when, we are told, epigenetic discoveries are showing that environment can profoundly modify organisms’ biology, might it be entirely possible, or even routine, for brain anatomy to be altered quite radically by unusual environmental influences? I am thinking here of unusual conditioned responses to sex pheromones emitted by fellow humans. In the case of pedophilia, this would mean sexual arousal to child-related sensual stimuli (visual, auditory, tactile, etc.) once these had been conditioned from an association with the pheromone, this being theoretically the primary (olfactory) stimulus.
Genetically identical bees vary enormously from each other both in physical form and the roles they play. The queen can be twice the size of a worker bee. Workers typically have a lifespan of only weeks, whereas a queen can live for years. Also, the differences in the roles played by workers as opposed to queens are many and complex. As the genome is exactly the same for these massively differentiated types of bee, the differentiation would appear to arise from different patterns of gene expression.
If similar processes are at work in humans (not such a big “if”, it seems, given the fundamental cross-species nature of the molecular mechanisms involved) might not pheromone-mediated changes in gene expression within the brain be capable of giving rise to lasting and quite large changes in brain anatomy, such as different white matter structure for those experiencing pedophilia? If this is the equivalent of growing an “extra arm”, epigenetics seems potentially entirely capable of being up to the task.
Does Neuroskeptic agree?

0 0 votes
Article Rating
Notify of

Oldest Most Voted
Inline Feedbacks
View all comments

a new study that impulsive offenders indulge themselves in childhood with illegal sex experience:


new neuroimaging data on the difference between offending and non-offending pedophiles:

[…] have featured previously on Heretic TOC (see “Scientific egos as fragile as eggs” plus here, here and here for my engagement with him on his research), has now come up with a wheeze to use a […]

[…] have been around here a while will recall that my “no actual information” back in 2012 included a critique of his brain-imaging research, which had supposedly shown a “deficiency” in the white matter part of paedophiles’ brains. […]

[…] His responses are best characterised as throwing hissy fits, hurling sarcastic abuse while refusing to address the scientific issues I raised. He could not possibly deny this. These exchanges were not in private email: they were on Sexnet, visible to its 400 or so members. For a blow-by-blow account of our verbal fisticuffs see my blog: Scientific egos as fragile as eggs and The dubious analogy of the ‘extra arm’. […]

[…] if you feel you need it, see two of my Heretic TOC postings Scientific egos as fragile as eggs and The dubious analogy of the ‘extra arm’. These posts describe my initial engagement in debate with Dr Cantor on the Sexnet email list-serve […]

[…] paedophilic deficiencies of white matter in the brain. See Scientific egos as fragile as eggs and The dubious analogy of the ‘extra arm’. After citing the Guardian article, Neuroskeptic says “Now oddly enough, I recently had an […]


Thank you, Tom for sharing this with us. I am aware that the brain has a high level of plasticity. For this reasons I have had doubts about Cantor’s suggestion that paedophilia could be caused by a head injury. First of all, unless it was a very serious injury, the brain would recover. Secondly, it is most unlikely that a person would become disabled in such a specific way. Sometimes I wonder if Cantor has ever met anyone with brain damage. If I had brain damage in early childhood it is unlikely that I would a graduate, drive a car, cook meals, live independently etc.


A non-exhaustive list of celeb pedo-ephebos from the dawn-of-time to date, would fill a few sides of A4.
And even tales of a small 10% allegedly coercive (postwar Brit composer Benjamin Britten?) omit, for us, the far more interesting counterpart list of even more non-victim Adultos.
Some celeb non-victim past-Adultos are now well known, but more than 90% are largely unknown. Ongoing unchecked, instinctively self-motivated, proactive, plus peer-or-pedo beneficially persuaded.
Another lesser known truly major celeb Pedo ?
17th Century post-Reformation Brit King James 1 (V1 of Scotland). Married, familiy man, revered patriarch, who authorised the now world-acknowledged Anglican ‘King James Bible’. Millions of copies still read and respected, including by the Brit very high-elite.
Yet according to world-authority, Brit historian Dr. David Starkey, paraphrased:
” James’ personal courtiers were all young boys with slim legs and pert bottoms. ”
Nominated for ‘Adultophile Of The Year 2012’ – Megan Stammers.

Gil Hardwick

It is not only useful to society for men to take care of such boys, it is positively harmful to deny them. The disproportionately high adolescent depression, suicide, delinquency and incarceration rates in the contemporary West bear this out.
I have no evidence that women make better parents than men, or that children inherently prefer being raised by a woman.
It is certain, on the other hand, that children seeking to recruite an alternate care-giver will from middle childhood, from age 7-8-9, initiate what can be easily read as sexual overture. It is usually full-on in fact.
Given too that such engagement is inevitably transient while the resulting close friendship lasts for the rest of their lives, my view is that the function and intent is not to exploit but to bond.
Those kids will express real hurt, however, if their expressed desire for intimacy is repudiated. It is not something that can be at all dismissed lightly.
I do think we need to place the Western nuclear family model and its many deficiencies under severe scrutiny, if we want to understand more of why children seek out adults.


Hi Jedson!
I don’t think Shakespeare and Socrates can be called pedophiles in the sense of the word as used today. However that may be, you could also have mentioned Daniel Carleton Gajdusek, who won a Nobel Prize in medicine.


Tom — hang in there. You are making good points and expressing them well. Let me add another thought.
Let us suppose that the brains of people who have been identified as “pedophiles” and “non-pedophiles” really are different in terms of innate genetic factors the pre-date the impact of the environment. And let us also suppose that these differences really are identifiable on the basis of a physical examination of the brain. Mind you I am not yet ready to grant these premises, but for the sake of argument, suppose they are true. Even then it does not follow that the “pedophile” brain is “abnormal” or in any sense inferior. In fact there is absolutely nothing that can be concluded from this on the basis of the brain findings themselves. Whether a genetic variation is desirable or not (in evolutionary terms) has to be determined on the basis of whether the physical/behavioral outcome of the variation is in fact harmful or helpful to the evolutionary potential of the species — in other words, on matters that are not discernible directly by neurological examination. Again, if the propositions that I have tentatively granted are true, then for just such variations to be a significant part of our gene pool would argue that they were beneficial to the species, or they would have been weeded out. And, from an anthropological perspective, it is quite easy to argue that this could be the case. It might, for example, be very useful to a society to have a certain number of men who took a special interest in the care and education of abandoned, orphaned or dysfunctional boys. And, as we know, evolution uses sexual interest as a means of luring individuals into productive activities — like having sex or breast feeding.
As for the supposed correlation with low intelligence, I would just mention Shakespeare, Thomas Mann, Walt Whitman, James Barrie and Lewis Carrel in passing. And perhaps Socrates. And maybe Tom.


Gil – Rocks !
Hits ’em clean outta the ballpark !!

Gil Hardwick

I want to add something more to this discussion, since it challenges an implied subnationalist genetics, eugenics, brain functioning, inferior beings, blah blah blah . . . .
It is commonplace in colonial historiography covering several centuries that all those born and raised in the new lands were on average 6″ taller than their immigrant parents. Michael Davidson too, reporting on the new generation born in Zionist Palestine, before the formation of Isarel, stated clearly that they had already lost their traditional Semitic features and stood largely indistinguishable from others.
People free of oppression, restoring themselves, no longer victims, refusing any longer to play the victim to somebody else’s oppressive regime, within one generation stand tall among their fellow human beings.
To wit, the moment anyone at all starts delivering insults instead of offering friendship and support, tell them to fuck off.
Use of the word ‘fuck’ here is pointed and deliberate, all puns intended.
It’s not about anything else, ever.

Gil Hardwick

Errata: Mensa = IQ > 98% (top 2%ile), ISPE = IQ > 99.9% (top 0.01%ile).
My apology if misleading.

Gil Hardwick

To avoid the drivel I refer to Robert Epstein, ‘The Myth of the Teen Brain’. Download from,
It is commonplace that the post-partum brain is a mass of clear jelly with minimal neuron development, while 18 months later the brain consists of incredibly dense nerve mass resulting from environmental stimulation.
While I accept a measure of inherited temperament, and I have discussed this over the years with colleagues in Mensa, ISPE and elsewhere concerned with precocious childhood development (Mensa = IQ >2%, ISPE = IQ>0.01%, ‘my’ children 140-170 IQ), there is no doubt that high levels of body contact and sensory stimulation radically enhance nervous system, bone and muscle development in children.
As they mature those kids characteristically grow tall, lithe and slim, and of interest here thoughtful and considerate. Who they engage as a ‘sex partner’ from time to time is so marginal as to be irrelevant.
I am thus plainly a staunch advocate of extended family nudity and intimacy, bathing together, hugging and touching, good wholesome food and plenty of exercise, lots of good conversation, fun and laughter, reading and telling stories, replicating as closely as possible traditional child-raising practice.
It is amusing to read that Cantor considers ‘paedophiles’ to have typically low IQ. I suggest that he has preselected particularly repressed, unstimulated, underdeveloped individuals of very low SES already dragged kicking and screaming through the court system.


Intolerant, egocentric, non-prophet J.C. (no Christ Jim) may fail on further counts ?
1. Omits the numerous LBTStraight, femme-Pedo brains?
2. Omits the numerous LBTGStraight, femme-&-male Adulto brains ?
3. Omits the numerous high-achiever Pedo-&-Adulto brains ?
4. Omits the numerous failed theorist Non-Pedo brains ?
5. Anthropologically, maybe Gil might confirm that short-brain/long-tail/short-tail/no-tail apes come in all shapes-and-sizes ?

Would love your thoughts, please comment.x
Scroll to Top