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

This book is a good study in how theory comes into being. Scientists, influenced heavily by Darwin's Theory of Evolution, feel that there has to be a biological basis for intelligence, and they being to look for it. That is what this book is about. The early theories were based on biological determinism, or the belief that intelligence was biological. If intelligence is an inherited trait, then there has to be a way to measure it. This is what early scientists try to do with craniometry, which was the measuring of the brain size that was used as an indicator of intelligence.