This chapter is an overview of the prehistory of L, how people across the globe from our earliest sources to 1961 have tried to understand the beginning and end of history, and the rise and fall of civilizations. Factor L is put into a longer historical context of human conceptions about history, time, and civilization. In focus is the question of how it was possible to formulate L in its modern version, as embodied in the Drake Equation. This was not possible, I argue, until the end of the nineteenth century. L required a number of philosophical, scientific, and technical discoveries and inventions before it became possible to discuss the longevity of extraterrestrial technical civilizations. Of special significance was the “discovery of time,” the emergence of a set of ideas for understanding human temporality: first, linear time, time that has a beginning and an end, and in which nothing is forever; second, long time lines, in which there was a time before humans and human civilization, and that the history of our civilization is only a fraction of the history of universe; and third, that time has a direction, that humans are historical beings – that is, knowledge, culture, and society are not something preexisting but something created by humans, evolving, that rests on the experiences and actions of previous generations in a cumulative process leading to the development of knowledge, behavior, and life conditions, or what is sometimes called the “idea of progress.”

The first section concerns the beginning of time: notions of the dawn and age of the world, thoughts about the history of the Earth and humankind, when humans entered the history of the universe, and the emergence of the notion that human civilization has existed for only a fraction of the total age of the universe. The second section concerns the direction of time: where we are heading, ideas about how societies emerge, the rise of civilizations, and the notion of advancement, the thought that civilization is not a given but something created by humans. The third section puts forward notions of the end of time: doom, cataclysms, the meaning of history, and how and why civilizations and empires – or the whole world – fall. Finally, I conclude that L is a measure of the civilizing or socialization process, and the variables that underlie it: biocultural coevolution and the interaction between the evolution of cognition and socialization.