Intelligence - what causes it?

Does anybody know how one person can retain more information in a set period of time than another. Excluding study skills and assuming both have equal susceptibility to distraction while studying.

What physically or biologically causes it? More neurons in the brain? better connected neurons? Like what Actually exists that differentiates people with differing intelligence. Do people know yet?

to retain more information needs practice. as you know memory consist of long term memory and short term memory. what you need to do is teach your short term memory to retain more and then transfer to to the long term memory. as you know the short term memory can store 7 bits, so if you increase the load within the 7 bits, this will teach your short term memory to retain more information.
e.g. short term memory:

1 2 3 4 5 6 7 this is only storing single letters
a b c d e f g

but when you do this:

1 ant this is increasing the information stored and retaining it.
2 bird
3 cat
4 dog
5 elephant
6 frog
7 giraffe

by doing this, you can increase the information retained and transfer it to long term memory.

biological wise, I think the more active neuron, the faster the process of storing information. hope this helped if you don't understand, do say so

I see what your saying...... so basically you think its all down to accumulating knowledge from the start. So basically if I was forced to stop learning people deemed "less intelligent" could theoretically "catch up" to the same intelligence as me? Or am I way off?

I could be going off on a tangent here, so I do apologies, nevertheless, it's pretty interesting.
I take Sociology at Alevel, and I've literally just finished studying a topic on Intellectual Development.
In Sociological terms, how Intelligent you are depends on your social class/up-bringing. The theory of Cultural Deprivation argues that Middle Class children are more likely to be Intellectually developed/equipped than Working Class Children because of the values and attitudes of their social class.
For example, (according to this theory) Middle Class families are more likely to support their children by reading to them at a young age, giving them toys that enhance their intellectual skills, and conduct in intellectual activities with their children such as, 'sight seeing', 'reading', 'museum trips', 'watching documentaries' etc and therefore M/C children are more likely to be Intelligent.
Whereas Working Class Families are more likely not to support their children by reading them 'rubbish stories', not offering such intellectual activities, allowing them to watch rubbish TV etc etc.
(Hopefully you get the picture)

BY NO MEANS, do I agree or disagree with this. As essentially it's saying those from Middle Class families are more likely to be Intelligent than Working Class families. However, It is quite interesting!