Contextual Focus: A Cognitive Explanation for the Cultural Revolution of the Middle/Upper Paleolithic

Many elements of culture made their first appearance in the Upper Paleolithic. Previous hypotheses put forth to explain this unprecedented burst of creativity are found wanting. Examination of the psychological basis of creativity leads to the suggestion that it resulted from the onset of contextual focus: the capacity to focus or defocus attention in response to the situation, thereby shifting between analytic and associative modes of thought. New ideas germinate in a defocused state in which one is receptive to the possible relevance of many dimensions of a situation. They are refined in a focused state, conducive to filtering out irrelevant dimensions and condensing relevant ones. Introduction: A Cultural Revolution Human culture is widely believed to have begun between 2 and 1.5 mya, at which time a rapid increase in brain size coincides with onset of the use of fire and sophisticated stone tools. The archaeological record suggests that a perhaps even more profound cultural transition occurred between 60,000 and 30,000 ka during the Middle / Upper Paleolithic (Bar-Yosef, 1994; Klein, 1989; Mellars, 1973, 1989a, b; Mithen, 1996, 1998; Soffer, 1994; Stringer & Gamble, 1993; White, 1993). Leakey (1984) writes: Unlike previous eras, when stasis dominated, innovation is now the essence of culture, with change being measured in millennia rather than hundreds of millennia. Known as the Upper Paleolithic Revolution, this collective archaeological signal is unmistakable evidence of the modern human mind at work (p. 93-94). Mithen (1996) refers to this period as the 'big bang' of human culture, claiming that it shows more innovation than the previous six million years of human evolution. It marks the beginning of a more strategic style of hunting involving specific animals at specific sites. We also see the colonization of Australia, the replacement of Levallois tool technology by blade cores in the Near East, and the first appearance of many forms of art in Europe, including naturalistic cave paintings of animals, bone and antler tools with engraved designs, ivory statues of animals and sea shells, personal decoration such as beads, pendants, and perforated animal teeth, and elaborate burial sites. Some of these items are associated with social change and the beginnings of ritualized religion; White (1982) writes of a “total restructuring of social relations” (p. 176). Moreover, we see the kind of cumulative change that Tomasello (1999) refers to as a Ratchet Effect. What could have caused this unprecedented explosion of creativity? Some have noted that it would make things easier if this second cultural transition also coincided with an increase in brain size (Mithen, 1998; Richerson & Boyd, 2000). And in fact, human brain enlargement does seem to have occurred in two spurts. However, the second takes place between 500,000 and 200,000 (Aiello, 1996) or 600,000 and 150,000 ka (Ruff, Trinkaus, & Holliday, 1997); at any rate, well before the Upper Paleolithic. Thus the cultural revolution cannot be directly attributed to a change in the size or shape of the cranium. Leakey (1984) writes of anatomically modern human populations in the Middle East with little in the way of culture, and concludes “The link between anatomy and behavior therefore seems to break” (p. 95).