What is the main conflict in The Mismeasure of Man by Stephen Jay Gould?

The Mismeasure of Man by Stephen Jay Gould is a book that is concerned with how to rank people into groups on the basis of intelligence in a manner that is meaningful. Since intelligence is an abstraction about the human brain, Gould feels that it is possible to rank humans on this basis. The author, a paleontologist with a statistical background, analyzes data within a historical context and combines his skill as a scientist with his concern as a historian when looking at the issue of biological determinism. He looks at what they did right and what they did wrong in measuring human intelligence.