The Art Instinct
Aristotle could speak of human technologies and institutions as being inevitably reinvented over and over because he regarded human nature as fixed and the human species, along with all other species, as eternal: the world itself had always existed, and human beings had always walked upon it. In this he differed from his pre-Socratic predecessor Anaximander, who speculated that human beings had evolved out of the mud, as descendants of fish. Today we view human nature—the genetically endowed network of needs, desires, capacities, preferences, and impulses on which culture is built—as having been fixed only since the advent of agriculture and cities, the events that initiated our present epoch, the Holocene, around ten thousand years ago. Before that, our physical and mental makeup was continuously evolving through the generations of our nomadic human and proto-human ancestors in the Pleistocene. While human beings share an unbroken lineage through living things back beyond animals and into the Precambrian sludge, it is the Pleistocene contribution to human nature that is most relevant to understanding the cultural life forms of, for instance, governance, religion, language, systems of law, economic exchange, and the regularization of courtship, mating, and child rearing.
Accounts of human nature organized in terms of evolved features will naturally speculate about whether any universal human behavior pattern or disposition is an adaptation or the result of adaptations. Not all will be: across the globe, people ride bicycles above a minimum speed to keep from falling off. The brain mechanisms that enable them to do this may have evolved, but the minimum-speed behavior is a result of the gyroscopic physics of bicycles; its universality is no evidence for a genetically adaptive function. It is unlikely that minimum-speed bicycling behavior has any utility in explaining how our Stone Age forebears survived and reproduced. On the other hand, there are an indefinitely large number of universal dispositions and behavior patterns—particularly persistent desires, motives, capacities, and emotions—that point directly back to the Pleistocene conditions where they first arose. These are salient to understanding the cultural life of modern human beings and form the background for writing a Darwinian Genesis for the arts.
The Pleistocene lasted for 1.6 million years. Our modern intellectual constitution was probably achieved in this period by about fifty thousand years ago, fully forty thousand years before the founding of the first cities and the invention of writing. To understand the importance of the Pleistocene as the scene of the development of modern humans, we must keep in mind the immensity of its time scale: calculating at twenty years for a generation, eighty thousand generations of humans and proto-humans in the Pleistocene, as against a mere five hundred generations since the first cities. It was in this long period that selective pressures created genetically modern humans. These pressures might have pushed only very slightly in one direction over another, but a slight pressure over thousands of generations can deeply engrave physical and psychological traits into the mind of any species. Steven Pinker and Paul Bloom cite J.B.S. Haldane's 1927 calculation that 'a variant that produces on average 1% more offspring than its alternative allele would increase in frequency from 0.1% to 99.9% of the population in just 4000 generations.' Pinker and Bloom point out that a change not even observable in a single generation or in any individual can still over thousands of generations completely alter a species. The dramatic effects of minute selective advantages, they observe, can also work against the survival of a population: 'a 1% difference in mortality rates among geographically overlapping Neanderthal and modern populations could have led to the extinction of the former within 30 generations, or a single millennium.'