Here’s a link to an interesting Q&A with a New Zealand professor about the IQ of children. The start of the interview follows:

Q: Are children today smarter than their parents?

A: I don’t think they are smarter if by that you mean they have better brains. They think better on their feet; they can solve problems on the spot without being told what to do; they are better at working with shapes, thanks in part to the Internet and the computer. But they have no larger vocabularies and are no better at arithmetic.

Q: So why are their IQs higher than those of their parents and grandparents?

A: The people who invented IQ tests saw the world through scientific spectacles. They were interested in logical reasoning. But generations ago people were very utilitarian. If you asked a person in 1900 what a dog and rabbit had in common, they would say you could use a dog to hunt rabbits. Today you would say they both are mammals. That is shorthand for a lot of insight. That may seem trivial, but classifying the world is prerequisite to understanding it scientifically.

Q: You are referring to the portion of the IQ test that measures the ability to determine similarities?

A: Yes. And if you say “Mammals,” you get two points, and if you say “Dogs hunt rabbits,” you get none. The score on this portion of the test has gone up 24 points in America since 1947.