CDPXXX10.1177/0963721416657085Coolidge, WynnAn Introduction to Cognitive Archaeology 657085research-article2016 Current Directions in Psychological Science An Introduction to Cognitive Archaeology 2016, Vol. 25(6) 386 –392 © The Author(s) 2016 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0963721416657085 cdps.sagepub.com Frederick L. Coolidge1 and Thomas Wynn2 1Department of Psychology and 2Department of Anthropology, University of Colorado, Colorado Springs Abstract Cognitive archaeology studies human cognitive evolution by applying cognitive-science theories and concepts to archaeological remains of the prehistoric past. After reviewing the basic epistemological stance of cognitive archaeology, this article illustrates this interdisciplinary endeavor through an examination of two of the most important transitions in hominin cognitive evolution—the appearance of Homo erectus about 2 million years ago, and the recent enhancement of working-memory capacity within the past 200,000 years. Although intentionally created stone tools date to about 3.3 million years ago, Homo erectus produced a bifacial, symmetrical handaxe whose design then persisted for nearly the next 2 million years. An enhancement in working-memory capacity may have been responsible for the relative explosion of culture within the past 50,000 years, which included personal ornamentation, highly ritualized burials, bow-and-arrow technology, depictive cave art, and artistic figurines. Keywords cognitive archaeology, evolutionary cognitive archaeology, executive functions, working memory, Homo erectus, Homo sapiens Cognitive archaeology (aka evolutionary cognitive Archaeologists recover artifacts and patterns of arti- archaeology) is most often defined as an approach to facts (a) and from them reconstruct the activities respon- studying human cognitive evolution that applies theo- sible (b). The key piece of reasoning is the inferential ries and concepts developed in the cognitive sciences to link (b). How is this done? Archaeologists base this infer- archaeological remains of the prehistoric past. It is ence on their knowledge of technical systems in the pres- based on the premise that the material traces of past ent and the past. They often confirm inferences through activities can be used as clues to the minds that orga- experimentation, by duplicating the production and use nized those activities. It is an interdisciplinary endeavor, of the artifact (e.g., Stout, Schick, & Toth, 2009; Wadley, drawing on the data provided by Paleolithic archaeol- 2010). This requires a second inference (d), again based ogy (Paleolithic literally means “old stone age”), from primarily on knowledge of modern technical systems. In the first stone tools about 3.3 million years ago to those this step, ethnographic information about non-modern about 12,000 years ago, and upon interpretive concepts systems is also important and, for very early remains, provided by the cognitive sciences, psychology, and knowledge of non-human primates. A final inference (f) other disciplines. that relies on concepts developed in the cognitive sci- But how can one construct valid arguments about ences is necessary to get from (e) to (g). It requires that cognition in the past? After all, the actors died long ago features of the reconstructed knowledge system be linked and cannot be participants in well-designed experiments. explicitly to elements of an established cognitive model. Instead, cognitive archaeology relies on forms of reason- ing used in the historical sciences, such as geology and Corresponding Authors: paleontology. It is primarily observational, reasoning Frederick L. Coolidge, Department of Psychology, University of about past processes from patterns visible in the present. Colorado, Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Experimentation plays a role in testing hypotheses about Springs, CO 80918 E-mail: [email protected] past processes but is not the primary basis of an archaeo- logical argument. An archaeological argument about cog- Thomas Wynn, Department of Anthropology, University of Colorado, Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, nition relies on a series of linked inferences (Botha, 2010; CO 80918 Wynn, 2009; see Fig. 1). E-mail: [email protected] An Introduction to Cognitive Archaeology 387 Artifact or Technical Procedures Cognitive Feature System and Knowledge Prerequisites abcd efg Fig. 1. Botha’s (2010) and Wynn’s (2009) linked series of bridging arguments about cognition in the past. Artifacts (a) are linked to the technologies that produced them (c), those technologies to the concepts and knowledge they derived from (e), and that knowledge to its cognitive prerequisites (g) through a series of inferences (b, d, and f). Herein lies the challenge of cognitive archaeology, for habilis, had a brain size around 650 cc, which was about only with carefully constructed arguments can the assess- 50% greater than that of the australopithecines. However, ment achieve modest levels of reliability. But it is not a the body proportions of the habilines remained similar to fool’s errand; this form of reasoning is the only way that those of the australopithecines, suggesting they probably science can access the minds of prehistoric actors, and still slept in trees. The stone tools of the australopithe- thus, despite the challenge, it is a necessary component cines and habilines were relatively simple: mostly sharp of any attempt to document human cognitive evolution. stone flakes struck from a pebble core (see Fig. 2). How- Given the interdisciplinary nature of cognitive archae- ever, there is nothing known about this earliest technol- ology, it is a challenge for scholars to follow all of the ogy that would have selected for the increase in brain relevant scholarly developments. However, collaboration size. These tools were used to butcher animal carcasses eases this load and also provides more nuanced under- obtained through scavenging, and this access to higher- standings of the peculiarities of the disciplines involved. quality nutrition arguably powered the increase (for We began working together in 2000, Wynn the archae- greater detail on the relationship of meat to the evolution ologist and Coolidge the neuropsychologist, and the fol- of cognition, see DeLouize, Coolidge, & Wynn, 2016). lowing summarizes our thoughts on two of the most The first apparent evolutionary development in cogni- salient transitions in hominin cognitive evolution (hom- tion well beyond the ape range occurred with the advent inin refers to modern and extinct humans and their most of Homo erectus (upright man) about 2 million years ago known or suspected distant ancestors). along with a lithic (stone) technology known as Acheu- lean (see Fig. 3). The First Major Leap in the Evolution The hallmark of this technology is the handaxe, which of Human Cognition: Two Million Homo erectus made by trimming around the margins of a large flake to produce a sinuous cutting edge. In doing so, Years Ago they also imposed a bilateral symmetry on the tool. Its In the second edition of our book, The Rise of Homo manufacture clearly required spatial cognitive abilities sapiens: The Evolution of Modern Thinking (Coolidge & (the active coordination of dorsal and ventral information Wynn, in press), we propose there were at least two from the primary visual cortex) and hierarchical organiza- major leaps in the evolution of cognition in hominins. tion of action that also relied on mechanisms of cognitive The first major cognitive leap was in the evolution of control whose use was not evident in the stone tools of Homo erectus out of an earlier, smaller-brained hominin earlier hominins (Hecht et al., 2014; Wynn, 2002). Homo about 2 million years ago. The earlier australopithecines erectus was not just a variant on the standard ape; it was (comprising many species of bipedal hominins at that something altogether different in its morphology, behav- time) had brain sizes in the range of modern chimpan- ior, and cognition. A number of evolutionary firsts were zees (around 400 cc), but some made and used stone associated with Homo erectus: dispersal out of the tropics tools. Their smallish bodies compared to their longer and into cooler habitats; modern body size and locomo- limbs indicate that they traveled on the ground while tion, including running (Lieberman, Bramble, Rachlen, & foraging but probably slept in nests in trees, like modern Shea, 2009); an increase in female body size and reduced chimps. They had varied diets that probably included sexual dimorphism (i.e., difference in body size between some meat, but they seemed to be very apelike in terms males and females); and an increase in relative brain size of brain size, brain shape, and behaviors. well beyond the ape range, about 950 cc (modern brains = No significant increase in relative brain size occurred 1,350 cc). Antón, Potts, and Aiello (2014) have argued that in any of the various hominin groups until about 2.5 mil- the pivotal feature of Homo erectus’s success was the abil- lion years ago, with the advent of hominins assigned to ity to adjust to dynamically fluctuating environmental the genus Homo; one tool-making hominin, Homo conditions. These authors did not specify their cognitive 388 Coolidge, Wynn Fig. 2. The first known stone tools, a pebble core and sharp flakes, dating to about 3.3 million years ago. These were the first tools that were retained and reused, rather than being discarded