What a fascinating article! That there is a continuum linking autism to dyslexia is a contentious. Much of our current understanding of  neurophysiology of the brain stems from research into the nature of vision. Being an Ophthalmologist this is an area of eternal fascination for me. Early visual experiments by Hubel and Weisel correlate visual stimuli with the brains electrical activity. Because they could not only control the former very precisely, but also measure the latter with microelectrodes they were really the first to tease out the mysteries of the brain in the sense of looking at it like an electrical wiring diagram.

They basic concepts underlying the architecture of the brain have since been extended to the other senses and motor functions.

It was a huge advance because prior to that medicine looked at brain damaged victims and deduced very crudely what bits did what. Head injury patients from World wars etc advanced the state of neurology considerably. Rather akin to smashing different bits of a car with a sledge hammer and seeing how it fails to perform.

The problem with Hubel and Weisel method of investigation, is it’s hard to control the input precisely for higher cerebral functions and then record them (they basically used lab animals with were sacrificed in the pursuit of science).  You can’t get Fido to contemplate Plato, and alternatively who would want electrodes shoved in his brain?

There have been many interesting studies looking at neuronal activity in less invasive fashions (Neuro imaging with PET etc). But they still lack the resolution of putting an individual microelectrode into an individual neuron and patiently working out what turns it or its neighbours “on or off” as it were.

The functioning of the brain and its relationship to our personal subjective experience of consciousness is really a search for our identity and who could turn from that? I suspect the next wave of understand will ultimately stem from our increased understanding of genetics.

I personally would not call Daniel Tammet a genius. I think that word is overused. I believe it really should be reserved for those rare individuals that have contributed to civilisation in some profound way that forever changes the way we view the world. For example Newton, Einstein and of course Rand! I also doubt he will function as a Rosetta stone because examining his subjective impressions is really still at the sledge hammer level of investigation into cognition.

I was interested, David, in your experiences with your dyslexic son. I too have dyslexia. I learnt to spell my name at the ripe old age of 10. 9s, 6s, Ps and bs were entirely interchangeable for me for the longest time. I am still rather poor at spelling, have no sense of direction and am rather absent minded. Yet I too am a very visual person. I can observe an operation and remember it in detail, a skill useful as a surgeon.  

I would agree with you Steve that there are little positive evolutionary pressures being applied to us as a species and that this is source of concern for the long term. Indeed, at least in New Zealand with our overgenerous welfare state, there are many large families that procreate early, and have lived on benefits for generations.  I still think that there are some weak evolutionary pressures. I would argue bright people are attracted to bright people and tend to have bright kids. Also there is a tendency for smart people to be successful. If you look at “Old world” countries (and I have visited many and lived and worked in England for a year) I would argue that the social stratification is more marked than in the “New World.” This is despite being taxed into oblivion and  after surviving politically correct educational systems Hell bent on labelling everyone as mediocre.  Maybe with time the “mean” intelligence may decline but perhaps there is emerging a wider more defined and self sustaining distribution for a range of abilities? Look out for the Morlocks!

I would also refer you to an illuminating article “The Outsiders” by Grady M Towers for what “High IQ” means, at least to an individual. It was an absolute revelation to me which explained three generations of my family. Finally I quote late David Wechsler who defined intelligence as "the global capacity to act purposefully, to think rationally, and to deal effectively with his environment". I think Ayn Rand would have approved.