Ok Marc I've looked at this issue of different IQ variance among races again and have to admit that my statement that caucasians have greater variance seems not to be true. I picked that information up some time ago but looking at some more information I think it was wrong. 
 
My objection to this average IQ thing is that people (including scientists) will make statements such as "greater east-asian intelligence may be caused by genetic factors". The problem with this is that as I've already said, average IQ can be manipulated by for instance selective breeding. You could create a race of caucasians with an average IQ of 130 if you wanted to and the same with east-asians. Therefore how do you determine which one has superior genetic intelligence? It seems to me to be impossible to do unless one race has an upper IQ range that significantly outstrips the other which I do not believe is the case here. 
 
The more I look into this intelligence thing the more mysterious it seems to be. There certainly seem to be different types of intelligence and I suspect that different races also have very different temperaments. I'm beginning to suspect that east-asians are better at things like maths whereas caucasians maybe more inventive. It's interesting for example that in formula one racing when the Japanese have entered their own teams they have always done very poorly despite enormous resources from the likes of Honda and Toyota. In the end both these teams moved their grande-prix operations to Britain, something that I always found suprising. Are caucasians good at concept based stuff and therefore good at things like grande-prix car design?

Most IQ distributions ie. bellcurves are approximations, thats why they look symmetrical. In reality an accurate curve for a given population would not be exactly symmetrical. Not only would it not be symmetrical but there would be different IQ spreads for different population groups. 
 
I believe that the caucasian IQ spread is wider than the east asian. The caucasian spread is about 15 standard deviations, the east asian about 10 SD. That means that although east asian average IQ is slightly higher, caucasians have a higher number of very high IQ's than east asians. This is why average IQ is misleading.

"Even if it turns out that the current disparity of 3 to 6 IQ points between East Asians and Europeans is genetic in origin it may well have evolved during the past two centuries, rather than the Ice Age as suggested by Lynn and Rushton" 
 
How can such a statement possibly hold true when the average IQ of a race can be manipulated by selective breeding. If you can make a race who previously had lower average IQ than another brighter by removing the lower IQ's then how can you say that one is genetically more intelligent than another? Average IQ does not measure a races potential! You have to look at the higher IQ's in the population.

I think you misunderstand my point Marc. I am really asking the question "How do you measure a races potential". Rather than average IQ it would be better to look at the IQ of say the top 30% of that population. In this way you are looking at their true potential when the least intelligent in that society have been removed from the equation. Average IQ can seriously distort the picture. You could have a group with enormously high IQ at one end and very low IQ at the other and average IQ might make them look not particularly bright, but their brightest might be immensely bright.

This obsession with average IQ is misleading and in no way leads to the conclusion that say South East Asians are more intelligent than say Europeans. Average IQ is only a measure of IQ distribution within a society and is not a measure of absolute IQ. 
 
For example you could remove the lowest 10 or 20% in terms of IQ from European populations and their average IQ would leap over that of say the Japanese which is currently a little higher than that of Europeans. Does Japans currently slightly higher average IQ therefore mean that the Japanese are more intelligent than Europeans? No it doesn't it just means their IQ distribution is a little more favourable in terms of average IQ at this point in time.  
 
In any society average IQ can vary over time depending on who manages to produce the most offspring. If the lowest IQ's produce more offspring average IQ will fall. If the highest IQ's produce more offspring then average IQ will rise. If you really wanted to evaluate IQ potential in populations you would have to find who had the highest absolute IQ's not the highest average IQ.