James Kwak in The Washington Post: Homo sapiens have big brains. We use those brains to develop new technologies, which enable us to produce more stuff and support larger populations on the same amount of land. Higher population density makes possible greater specialization and increases demand for innovation. As a result, cultural attributes that favor education and innovation become more valuable, so families with those attributes are more likely to reproduce, resulting in a population that is more favorable for further technological development.
These “wheels of change” have been the key drivers of technological progress since the beginning of time, economist Oded Galor argues in his new book, “The Journey of Humanity: The Origins of Wealth and Inequality.” Throughout most of our history, however, our species was caught in a poverty trap.Technological innovation caused increases in food production, which caused higher population growth — until the additional mouths to feed canceled out the productivity gains, bringing living standards back to subsistence levels. In the 19th century, however, the inexorable march of technology reached a tipping point. With the Industrial Revolution, according to Galor, the value of human capital reached the point that parents chose to have fewer children and invest more in their upbringing. Longer life spans made human capital even more important. As women’s wages began to approach those earned by men, it became more costly for them to leave the workforce to have children, further reducing birthrates. This demographic transition allowed technological progress to vastly outstrip population growth, producing our present world of material plenty.
Unparalleled in its scope and ambition, “The Journey of Humanity” explains the whole of human history as an inevitable progression from the first primitive tools to supercomputers in every pocket. At the same time, the book explains why that progression has made some parts of the world so much richer than others.
All human beings are descended from people who migrated out of East Africa in successive waves beginning more than 60,000 years ago. At each point in the migratory chain, only a subset of the population chose to move on. Because a subset of a group is likely to be less diverse than the whole group, populations became more homogeneous the farther they traveled: Before recent centuries, the highest levels of genetic diversity were found in East Africa and the lowest levels in South America (because people arrived in South America only after migrating through all of Asia and North America). According to Galor,diversity can inhibit economic growth by decreasing social cohesion, but it can also increase growth by promoting specialization and innovation; therefore, regions with an intermediate level of diversity have the highest levels of economic development.