Brain Pruning: the answer to autism?

"In adults [the human brain] has perhaps 100 billion neurons, each connected to its neighbours by 5000 synapses or so." New Scientist, 1 October 2008

"In the f[o]etal brain, all parts of the brain are interconnected, but as we age, the connections are pruned.  If the pruning genes get it wrong, the connections are off." - according to Vilayanur S Ramachandran, in New Scientist, 8 January 2011 (The fastest brain in the west, p26)

There is no disputing that the human brain undergoes a pruning process whereby the synapses, the connections between neurons, are culled while the brain is developing.

This is a normal part of the development process: meaningful connections are retained, and [at least some] unused ones are discarded.  This is a rationalisation that begins before the baby is born and continues for years afterwards.

And it's those synapses that enable brain functionality, particularly connections between different areas, which facilitate all manner of associative thought and reasoning.


The second quote above was made in the context of neuroscientist Ramachandran's study of synaesthesia, the leaking of one sense into another (the most common example being seeing letters or numbers as specific colours).

Occam's razor says to me that it need not take Ramachandran's concept of "pruning genes" for the pruning process to go awry. Development both before and after birth are affected by quite a range of factors.

Yet it struck me that disruption to that process may account for high-functioning autistics [so called "savants"] in particular.  The ability of Daniel Tammet, for example, to recall thousands of digits by visualising the string as a rolling landscape - that sounds like abnormal connections remaining in place between disparate parts of the brain.

Incorrect pruning may account for autism in a wider sense - not just those that are high functioning - but it seems easier to look to that process when describing aberrantly strong functionality than a weakening of capability, which can be due to a much wider variety of factors.

Evolution and monotremes, spam and off-topic Google searches

This post will discuss monotremes in evolution, but first a diversion to the reason for this topic.

I got a comment submitted from "Izumu":

"Hi Stephen,
I am Izumi from TBS TV, a Japanese TV company. We are intersted in the platypus egg photo you posted on your blog of 19 Mar 2008. I couldn't find your email address and that's why I'm making comment trying to be in touch with you. Could you kindly write me back to xxxxx@nifty.com ? Please don't post my comment since it includes my email address. Thank you very much for your coopereation. Izumi "

I post a reproduction of this comment sans email address, although I was inclined to include it anyway.

I get quite a number of spam comments posted, which is why comments are moderated.  I'm not inclined to reply to this request directly, because:
a) It was off topic;
b) The email address wasn't from an official TBS domain - Nifty is just a Japanese ISP.

Usually I just mark spam as spam.  I don't usually get a comment that's so close to falling either way.


There's a few pictures of platypus eggs on the web.  As it happens, mine is now at the top of Google Images.  It was a bit of a tragedy in some ways, because the actual topic of the post was the evolution of milk, but it gets caught in the wrong net.  If you want to communicate about platypus eggs, talk to someone who's communicating about platypus eggs.

The reason they appear to us to be strange is just a quirk of evolution: they are the last representatives of the earliest types of mammal.  The only egg-laying mammals (protherians) left are the monotremes, two species of echidna (porcupine-like creatures) and one of platypus, all native to Australia/Papua New Guinea.  Yet the first mammals were egg-layers.  Marsupials (metatherians: live but under-developed birth) and then placentals (eutherians: live birth) were a much more recent development, as the technology of birth evolved over tens of millions of years.

The oddness of the platypus may initially be due to their appearance, including webbed feet and a duck-like bill.  The fact that  they're mammals that lay eggs draws people in more.  But they are distinctive for two more reasons: they have poisonous spurs on their ankles (which seem to be for breeding purposes!), and they hunt through muddy water by sensing electrical fields.

The platypus, in evolutionary terms, is not so odd.  Pretty much all these features have evolved separately in other animals.  That's evolution: the time spans involved are so vast that if mutation can produce a lasting feature once, it can do it again.

No, the true oddness of the platypus lies in its survival to a time where most of its features are seen as uncommon.  There's a warning there: the survival of features that do not catch on (radiate) more broadly - in numbers or variety - is more indicative of desparately clinging to a vanishing niche than of evolutionary success.

Best of 2010: Film, concert, album

My best-of for last year is based on when I absorbed it, rather than when it was released.  Films:



1.  Inception (US, 2010)
Complex enough to keep me engaged - twice.

2.  Up In The Air (US, 2009)
It's George Clooney, and it's funny.  That's more than enough to help the journey through some of the bitter undertones.

3. Avatar (US, 2009)
Spectacular.

4. The Girl With The Dragon Tattoo (Sweden, 2009)
Harrowing in places, but a very intricate plot.

5. Red (US, 2010)
Exemplary of what Hollywood's capable in an action thriller.  Very enjoyable for what it is.

These films struck me with enough impact last year, ahead of the rest of the pack.  Hovering below are films like Shutter Island and The Girl Who Played With Fire.

Best re-watch of the year
Beat The Devil (US, 1953) - yet again.  You have to know how to watch it to appreciate it.  It's really just a string of vignettes, written on the fly by Truman Capote, and carelessly tacked together by John Huston.  It's apparent that their enthusiasm waned, and the later scenes are somewhat shabby.  But the early scenes should be taken for what they are separately; and they are often masterful; often very funny.  Coincidentally, it's on ABC this Sunday night for those in Australia who want to record it.  It's public domain now.

Best concert of the year
Dave Graney and the Lurid Mist at Coogee Randwick RSL.  My hero, the King of cool.

Best CD of the year
Admittedly I've had my head in the ground, so there's been little for me to choose from.  But I do respect Corinne Bailey Rae's The Sea.

Book of the year
My reading has been mainly The Herald, New Scientist, and Wikipedia.  Even though I've not finished it, I will nominate Carl Djerassi's 1989 novel Cantor's Dilemma (thanks, Ray).  A fascinating overview of the politics of scientific and university research, and creditably written by a senior academic chemist.

WikiLeaks: The news item of 2010

The leaking of sensitive information isn't new.  But the actions of a certain US soldier in leaking truckloads of diplomatic cables is a clear game changer.

Those cables run the gamut of international relations, laying bare a huge number of sensitivities of a large number of nations.  Yet there's irony that has largely been overlooked: next to none of the revelations are a surprise at all.  They're pretty much what we expected to be happening behind the scenes: what governments really think of each other and of key world issues.  (One might be seen as an almost-surprise: China being all but ready to ditch support of North Korea.  But doesn't that make eminent realpolitik sense?)

Having a ready outlet for leaks means never having to scrounge around for a publisher.  Anything is up for grabs, open to leakage.

This could lead to significant upheaval.  At the very least, it renders gentle diplomacy potentially useless as a tool of international politics.  The absence of that option is sure to lead to more direct conflict, if the only conversations to be had are necessarily open ones.  More direct, honest communication, true, but more blunt and abrasive, too.

On the flipside, there is plenty of scope for abuse of this concept.  Strategic release of disinformation may become the tool of choice for intelligence agencies.  This can be an equally destabilising force in international relations.

It's not clear that all this will come to pass. But certainly that single massive leak action is having a global effect, and fallout both overt and covert is inevitable.

Top Posts 2010 for this blog

The posts in this blog that got the most hits for last year are as follows:


1.  Evolution: A picture of a platypus egg, in the context of the evolution of milk.  Yet the narrative of egg-laying mammals is more interesting than a mere picture.

2. Science: Some pictures taken from Wikipedia that gave some size perspectives on the planets, their moons, and the various star types.

3. Music: Cancion Mixteca: a haunting Mexican song, and actor Harry Dean Stanton's version.

4. Technology: What does IBM do? - What, you don't know?  Answer: not just hardware, these days.

5. Music: Vigrass and Osborne: forgotten 70s pop music - remembered only by those who sought out this link.

6.  Technology: Type conversion in SQL Server: varchar to real

7.  Tintin: Project O-Light: the intriguing Tintin adventure that never was - or not yet.

8.  Evolution: Tunicates: a giant tube worm, and its relationship to us.

9.  Evolution: Gondwana and New Zealand: NZ's separation from the southern land mass Gondwana - it's not how most people think.  And was there really a terrestrial native New Zealand mammal?

10.  Worldwide gun statistics.  In fact, it was more about the relationship between gun ownership and homicides.  As you'd expect, the more immediate the weapon, the more likely the homicide.

This is actually little different from 2009's greatest hits.  Observations: a) I didn't post much last year; b) Google's page rankings over time entrench winners.

Top post of 2010: mention of a Beach Boys concert.  However, I'd prefer you to look at the one on Sculptures By The Sea 2010, the stupidity of an art prize award to a plagiarism, and Homo Floresiensis as, potentially, australopithecus.

2010 Obituaries: Solomon Burke, Joan Sutherland, and others

Notable departures in 2010:

Solomon Burke, 1960s US R'n'B singer: Notable for songs like Everybody Needs Somebody To Love and Shake Your Tailfeather.  Surprisingly, he held a record for the most US Top 40 singles without hitting the top 20 (see Joel Whitburn).  And he had a career revival a few years ago, with his star-studded Don't Give Up On Us album.  But his best legacy is his live shows.  In Sydney a few years ago, he didn't move from a centre-stage throne.  But he gave us a truly wonderful secular gospel experience, one of the best concerts I've ever been to - an inspiring demonstration of the spiritual unencumbered by religion.  He will not be forgotten for that.

Joan Sutherland,  Australian opera singer: some say one of the best of the 20th century.  I can't say I've taken enough time to appreciate her, but what little I've heard gives me some indication why she was so warmly regarded.


Richard Holbrooke: Abrasive US diplomat who was, nonetheless, widely praised for his intelligence and abilities.  A notable example of his success was peace in the Balkans.

Tony Curtis, US actor. A significant presence in the 1950s.  Of the films he appeared in, easily my favourite is the biting film noir Sweet Smell Of Success.  Seek it out.


Leslie Neilsen, Canadian-born Hollywood actor: has a successful later career in comedy films such as Naked Gun.  Others put the words into his mouth, but his straight delivery was his own: simply marvellous.


Teddy Pendergrass, 1970s US R'n'B singer: must get a mention for his so-soulful lead vocals on all the hits by Harold Melvin and the Blue Notes, including  If You Don't Know Me By Now, The Love I Lost, and Wake Up Everybody.

Peter Graves: An icon of the 1960s tv series Mission Impossible.  It wouldn't be the same without his Jim Phelps.

Others that could round out a 10 include J D Salinger, Lena Horne, and Dennis Hopper.


One apparent demise in 2010 that will not be missed: people now seem to be saying twenty-ten, twenty-oh-nine, etc, instead of two-thousand-and-ten, two-thousand-and-nine.  Once again, I'm no longer out of step with the mainstream. :)