Are we getting smarter? If you mean “Do our brains have more potential at conception than those of our ancestors?” then we are not. If you mean “Are we developing mental abilities that allow us to better deal with the complexity of the modern world, including problems of economic development?” then we are. For most people, the latter is what counts, so I will let the affirmative answer stand. But scholars prefer to ask a different question, to which they attach a special meaning, namely “Are we getting more intelligent?” I will answer that question at the end of Chapter 2.

Whatever we are doing, we are making massive IQ gains from one generation to another. That in itself is of great significance. IQ trends over time open windows on the human condition that make us conscious of things of which we were only half aware. This book attempts to make sense of what time and place are doing to our minds. It has new things to say about cognitive trends in both the developed and the developing world and where they may go over the rest of this century. It falsifies a major hypothesis that suggests that IQ differences between the two worlds are set in the stone of genetic differences. It addresses the most recent debate about the death penalty, particularly attempts to obscure the relevance of IQ gains to who lives or dies. It shows that cognitive trends have rendered inaccurate the diagnosis of memory loss. Perhaps most disturbing, it adds a new dimension to the tendency of western adults and teenagers to grow apart since 1950.