Human Capital Evolution in a Cooling Climate

In this chapter, I discuss the expansion of the hominin family tree after Homo erectus and the evolution of new species such as Homo antecessor, Homo heidelbergensis, and Neanderthals in Europe and Denisovans in Asia. Most importantly, I present the Climate Pulse Model, predicting that hominins will concentrate in a few fertile refugia during glacial eras and disperse widely during interglacials. I confront some of the predictions from the model with existing paleoclimatic archives of historical temperature and sea levels. In another application of the model, I analyze the growth of brain volume over three million years and argue that brain growth has effectively acted as a substitute in food production for a deteriorating natural environment.