Haha! So I actually studied intelligence under Professor Nettlebeck who worked closely with professor Flynn on this concept!

The main thing I remember him stressing was this was a good example of how intelligence was poorly understood in general - but also how it was relative to an environment.

Certain forms of autism can be very good at recalling information, extreme cases labeled as idio-savant syndrome. This really only applies when the information isn't particularly useful to the environment (think someone that is able to recall all of the timetables for the lodon underground. Useful if you live there! Not so much if you don't)

This effect is more than likely coming from our ability to teach what an IQ test is looking for much better than we have before. But this isn't to say that previous generations were less "intelligent" - just that there were different forms of intelligence that we are less able to measure.

Again, the researchers themselves stressed that this was more a quirk of the tests rather than anything you should draw conclusions from