Scientists have studied race and IQ. The foremost scientist who has looked at the issue is James R. Flynn, who discovered an important phenomenon, increases in IQ scores over time, that had not been noticed by psychologists in data sets that Flynn reexamined. As Mackintosh (1998, p. 104) writes about the data Flynn found: "the data are surprising, demolish some long-cherished beliefs, and raise a number of other interesting issues along the way." His book, by the way,

http://www.amazon.com/IQ-Human-Intelligence-N-Mackintosh/dp/...

is the best first book to read about IQ testing. The best second book to read about IQ testing is Flynn's latest book,

http://www.amazon.com/What-Intelligence-Beyond-Flynn-Effect/...

and the best third book on IQ testing to read, after the other two books have given you a conceptual foundation, is Keith Stanovich's latest.

http://www.amazon.com/What-Intelligence-Tests-Miss-Psycholog...

A more complete annotated bibliography

http://learninfreedom.org/iqbooks.html

lists other books, not all from the same point of view.