Centers of Innovation. During the Neolithic and post-Neolithic periods, places that scholars now call "cultural hearths" developed in various parts of the world. They were centers of innovation in areas such as food production, irrigation, the man-made environment, government, and religion. In effect, a cultural hearth was a regional "cradle of civilization," where distinct cultural traits, elements, and values were developed and shared. Cultural hearths greatly influenced surrounding regions; the closer an area was to the hearth the stronger the influence. All cultural hearths were urban, relative to the population density in the rest of their specific environments. They were situated close to rivers or lakes that flooded annually, and they used systematic agriculture and irrigation to produce surplus food supplies for a predominantly sedentary population. In turn, each had to adopt residential patterns and organized behavior to protect crops from...