Early Stone Tool Use and the Evolution of Human Cognition

Transcription

1 Early Stone Tool Use and the Evolution of Human Cognition Kaitlynn R. Alarie University of Manitoba Key Words: behavioural modernity; evolution of human cognition; early lithic technology Abstract Modern humans display a unique degree of social and cognitive complexity. As species we are capable of creating diverse and complex technologies to overcome the limitations of our biology and our external environments. This observed mental uniqueness, has led many researches to coin behavioural and cognitive complexity as the hallmark of humanity and behavioural modernity. Human intelligence has evolved through time and selection, and we as a species owe our current abilities to the evolutionary precursors which came before us. Researchers in the burgeoning field of paleocognition have sought to identify the emergence of our human-like cognition within our hominin lineage through the analysis of the hominin brain size and stone tool technologies produced by extant hominins. Paleocognitive researchers have begun to systematically approach such complex issues as defining human cognition, testing long held assumptions about great ape and human cognitive analogies, and ultimately identifying the evolution of our uniquely human intelligence. Uniquely Human Many living species display evidence of sophisticated behaviours and intelligence; however, humans in particular display a unique degree of social and cognitive complexity (Stout 2011:1050). Humanity has developed the ability for symbolic thought, complex technological adaptations, and extremely diverse and adaptive social behaviours which are not observed in any other extant species (Stout 2011:1050). In general, modern humans are capable of creating the diverse and complex technology we experience every day, because we possess an unparalleled level of cognition and innovation. This observation of mental uniqueness has led many researches to coin this human-specific behavioural and cognitive complexity, as the hallmark of humanity and behavioural modernity (Stout 2011:1050). However, this uniqueness of consciousness and technological complexity was not always present in our hominin lineage, and we owe our current abilities to the evolutionary precursors which came before us (Tattersall 2010:622). Cognition is a relatively abstract term, and can be understood as both a biological and symbolic ability. As reasoning and cognition are non-physical traits, they ultimately leave no direct physical imprint in the archaeological record (Tattersall 2010:622). As such, researchers must infer cognition and intelligence through the recovered physical remains of an individual or species, or through the physical material culture produced and manipulated by those individuals. Scholars have strived for decades to define and

2 UMASA Journal Volume 32 (2014) Alarie 2 identify the first emergence and development of modern human cognition and behaviour in our hominin lineage. Throughout their pursuit to trace the evolution of human cognition, investigators have encountered two major hindrances, being a small and fragmentary fossil record of early hominins, and the difficulty with inferring intelligence ability based on fossilized cranial anatomy alone. As such, researchers have turned primarily towards lithic analysis, to better elucidate the history of hominin cognition and technological innovation. This focus on early lithic technology is due in part to the abundance and durability of hominin stone artifacts and the complexity required to produce lithic technologies, which makes lithic tools ideal study materials (Tattersall 2010:622). Through decades of intensive study and theory building, the complexity of stone tools, and relative brain size have emerged as proxies for cognitive sophistication and the hallmark of humanity. Analysis of the earliest stone tools created by hominins has become the most prevalent means to quantify the cognitive capabilities of our earliest ancestors. The emergence of stone tool technology within the hominin lineage was truly a monumental technological achievement and has been equated by some researchers such as Washburn (1959), as the spark of intelligence and innovation which has ushered in human modernity. Tools changed the whole pattern of life[,] bringing in hunting, cooperation, and the necessity for communication and language. Memory, foresight and originality were favored as never before, and the complex social system made possible by tools could only be realized by domesticated individuals. In a real sense, tools created Homo sapiens (Washburn 1959: 31). This intense focus on brain size and stone tool complexity within paleocognitive research communities has led me to several research questions regarding the study of the emergence of higher consciousness and cognitive modernity. How can we quantify and operationalize such ethereal concepts such as social and cognitive complexity? How can we utilize these proxies to identify the emergence of modernity and the burgeoning of higher reason in extinct hominins? What degree of cognitive complexity did the earliest hominin stone tool producers possess? And can extant apes be used as valid parallels for this early hominin mental condition? I will employ multiple lines of evidence to test and explore these questions, such as brain organization, primate and human behaviour, and lithic functional analysis. Culture, Cognition, and Technology What exactly has evolved to produce our modern human capabilities (Stout 2011:1050)? Is this technological and behavioural complexity a product of cognitive or cultural evolution, or the interaction between these two forces (Stout 2011:1050)? If we are equating the complexity of material culture as a document of the complexity of cognitive ability, how can we reconcile the relationship between culture and intelligence? Is cultural complexity merely a measure or expression of intelligence which is dependent on cognitive function and constrained by biology? Or to what extent is cultural complexity unbound to biology and cognition? Both Darwin (1871: ) and

3 UMASA Journal Volume 32 (2014) Alarie 3 Wallace (1870:85-86), early human evolutionary theorists, were famously troubled by this theoretical conundrum and toiled over the role and significance that culture may have played in influencing the course of human evolution. The field of human cognition remains divided in this respect. There are those researchers which view cognition as a closed system, which is exclusively based on biology and phenotypic function of the brain (Griffith 2005:583). Researchers, who support this camp, are ultimately searching for the development of the human neural phenotype or the speciation of cognition. This view of cognition discounts the interaction of culture, which some view as a conservative approach (Griffith 2005:584). Under this schema, hominin cognition evolved as an operational capacity to increase fitness in an environment, and is confined solely within a species-specific phenotypic capacity and cannot be transcended (Griffiths 2005:585). On the other side of the theoretical divide, researchers feel that culture reacts mutually with biology and that cultural sophistication has co-evolved with cognitive sophistication (Foley and Lahr 2003:109). Proponents of this approach view cognition as an unbound system which includes biology, the systematic organization of ideas, tools, and beliefs that can be mediated by culture (Griffith 2005:584). This second definition of cognition implies that human intelligence does not distinguish between physical and cultural identities and processes (Griffith 2005:584). Griffith (2005:584) asserts that an individual s brain is flexible within its interaction with the physical and cultural environment, and can be a carrier, receiver, transformer, or generator of ideas based on physical and cultural cues. Griffith (2005:584) proposes a view of human cognition that is comprised of a constant dialogue between three mechanisms: the brain, culture, and the physical world. These views of cognition tend to dichotomize our discussion as a nature versus nurture, or closed versus open system debate (Griffith 2005:584). The divide here is considerable in its implications for future study, and the interpretation of the significance of archaeological evidence. We may be able to reconcile this theoretical opposition if we adopt an encompassing operational definition of technology. Griffith (2005:584) proposes that technology should be viewed as the reflection of interactions between phenotype [biology] and the world in an objectified form. In this way tools can be both physical and mental, representing ideas as well as technology. These tools, whether physical or metaphysical, have the ability to reflect and shape cognition through increasing an individual s fitness in a given environment (Foley and Lahr 2003:109). Paleocognitive researchers posit that the interaction of intelligence with the environment is so heavily mediated by technology, that innovations in technology can produce effects which can alter the very nature of intelligence and cognition itself; essentially placing technology and cognition inside a constant feed-back loop (Griffith 2005:583). Technology permits abstract concepts and ideas which frame our world view and basic nature, which in turn is reinforced by the projection of our cognitive nature onto our technology (Griffith 2005:583). In this way technology can be viewed as a manifestation of intelligence, and can be used as proxy or record of cognitive complexity; at the same time we must

4 UMASA Journal Volume 32 (2014) Alarie 4 acknowledge that technology is also driving that cognitive complexity. Most technological archaeological studies are predicated on this assumption that the complexity of material culture manufactured by an individual, population, or species is influenced and constrained by their inherent cognitive abilities. Most commonly, archaeological analyses have been conducted to compare the complexity and ingenuity of material culture remains of Homo sapiens from different time periods, as well as between humans and extinct hominin species (Tattersall 2012:622). It is import to understand that this approach only addresses the physical manifestations of cognitive skill and not the social or symbolic. Archaeology can only examine the physical remains of culture and behaviour, and can only interpret those remains through use of analogy to infer social ideas and intent. However, using this approach we can still learn a great deal about the evolution of human cognition through the study of ancient stone tools. Tools and Cognition Archaeology can provide for us two key bodies of evidence to better understand the evolution of human-like cognition: the timing of cognitive or innovative developments and the evolutionary context of those developments (Wynn 2002:389). As archaeologists we must develop a methodology and technique that documents those attributes which can be linked through theory and testing to cognitive mechanisms (Wynn 2002:389). The field of cognitive archaeology is often termed paleocognition, and represents a burgeoning and dynamic young subdiscipline which holistically approaches the directive of elucidating the evolution of human-like cognition (Tattersall 2010:622). As stated previously stone tools or lithics provide physical evidence of human and pre-human technology, and have been viewed by cognitive archaeologists as a good proxy for assessing the cognitive capacity of their producers (Tattersall 2010:622). Lithic tools and debitage are the most commonly discovered artifacts relative to human prehistory, due to their purely inorganic content, which is relatively inert and does not promote degradation of the material (Tattersall 2010:622). Paleolithic stone implements are abundant and show chronological and geographic variation throughout the course of hominin evolution, lending themselves well to comparative studies (Wynn 2002:389). Our record of hominin material culture begins approximately 2.5 Myr with the earliest known Oldowan stone tools, created by distantly related hominins with chimpanzee-sized brains (Tattersall 2010:622). These Oldowan stone tools represent the earliest evidence of direct modification of stone in regards to tool use, and were produced through much simpler modification techniques than later stone tool traditions. The Oldowan period of hominin history coincides with the highest point of hominin species variation. Grove (2011:316) posits that this extreme expression of hominin form variation can be interpreted as a biological reaction to an overwhelming environmental selective pressure during this time. Grove (2011:316) feels that a harsh and changing environment during this period selected for hominins with high behavioural variability and technological adaptations. Grove (2011:316) asserts that this

5 UMASA Journal Volume 32 (2014) Alarie 5 environmental pressure was the evolutionary driver for the first emergence of flaked tool production, and is responsible for the cognitive and technological complexity which emerges in later descendant hominin species. However, this view is not shared by all paleocognitive researchers. Between the simple, ancient Oldowan traditions created by distant early hominins and the recent diverse Upper Paleolithic tradition created by anatomically modern humans, there has been an observed trend of increased stone tool complexity punctuated by major noteworthy technological innovations along the continuum of hominin evolution (Tattersall 2010:622). The process of cognitive modernization was undoubtedly gradual and proceeded through multiple hominin forms. However, researchers may place more empirical weight on some stone technological advances than others. This leads to much disagreement regarding the cognitive significance of certain tool traditions and flaking techniques. In addition, there is very little agreement regarding the assignment of hominin species to tool traditions, further complicating the matter of cognitive reconstruction. which produced these assemblages. During the Acheulean period hominin species underwent a dramatic increase in brain size relative to a limited increase in body size (Shipton et al 2009: 220). On the other hand, some archaeologists assert that the process of modernization occurred much later than the Oldowan or Acheulean, instead around 300 Kyr with the emergence of composite stone tools marking the advent of the African Middle Stone Age (MSA) (Wadley 2010:112; Henshilwood and Dubreuil, 2012:132). Composite tool making and hafting requires significantly more planning and coordination of multiple segregated tasks than simple stone flaking techniques done in earlier tool traditions. Wadley (2010:112) views this as a major cognitive milestone in the history of human technology. Henshilwood and Dubreuil (2012:132) assert that MSA tools show signs of symbolic intention, which coincide with observed increases in brain size and frontal lobe organization in fossil hominins from this period. In this way, both Wadley (2010) and Henshilwood and Dubreuil (2012) situate the MSA as the technological period which marks the emergence of modern cognition. Following the Oldowan tradition the Acheulean (1.7 Myr) tradition emerged with a heavy focus on bifacial flaking technology (Goren-Inbar 2011:1038). The Acheulean spanned an enormous geographical range and persisted relatively homogenous in form for over a million years, which some may view as representing mental stagnation (Goren-Inbar 2011:1038). Researchers such as Shipton et al (2009:219) view the increasing degree of symmetry during the Acheulean as representing major In addition, Wadley (2010: 111) has proposed that the first uses of compound adhesive to haft stone blades to shaft elements occurring much later than the MSA (~70 Kyr in Africa) represents yet another complex and significant technological innovation milestone in human cognitive evolution. Wadley (2010:111) asserts that this was a multi-stage process and required significant use of abstractness, recursion, and mental imaging, all indicative of fully advanced modern cognition. Recent cognitive studies have cognitive and symbolic advancements for the hominins

6 UMASA Journal Volume 32 (2014) Alarie 6 attempted to test these hypotheses linking observed complexity in tool form with high cognitive complexity. physical world, with a great ability to visualize and predict future outcomes (Moore 2007:13). So, How Hard is it to Break a Rock? Stone tools are created through different techniques to fracture raw stone material (Wynn 2002:390). Fracturing the stone produces stone shards with sharp edges, referred to as flakes. These techniques of flake removal are collectively referred to as knapping (Wynn 2002:390). Variations in knapping techniques highlight many of the basic differences between tool making traditions (Wynn 2002:390). In the simplest technique a stone knapper strikes a raw core of stone with another stone or hard organic hammer to remove a flake from the stone core (Wynn 2002:390). A flake may be removed if a knapper can strike with adequate force, in the correct position on the core, and at the correct angle (Moore 2007:13). This is where significant skill and preplanning comes into the knapping equation (Moore 2007:13). Even in this simplest example the knapper demonstrates a high degree of mental capability. The knapper must choose an adequate material for both the core and hammer (Moore 2007:13). The knapper must use abstractness to visualize the potential flake within the core before it is produced (Moore 2007:13). Additionally, the knapper must acquire an understanding of the basic mechanics of fracture and the behaviour of the stone material they are working (Moore 2007:13). Furthermore, the knapper must react to the stone and the changing condition of the core, and adjust their striking position and angles accordingly (Moore 2007:13). This demonstrates a strong geometrical and logical understanding of their In a recent experimental study, Stout et al (2000:1215) examined the relationship between stonetool making and brain function. The authors aimed to identify the specific regions of the brain which were activated in an individual while stone knapping (Stout et al 2000:1215). They used Positron Emission Topography (PET), a brain function imaging technique, to trace the pattern of task-related brain activity (Stout et al 2000:1215). There results suggest that during simple stone flaking there is heavy activation of the cortical and subcortical regions of the brain (Stout et al 2000:1215). These areas are associated with somatosensory and motor processing, and are linked with complex spatial cognition that requires mediating sensory and spatial information (Stout et al 2000:1215). These observations indicate that even the simplest stone knapping techniques require a great degree of sophisticated cognitive function and reasoning. Given this new experimental evidence which associates high brain function and activation with relatively simple Oldowan grade flaking techniques, I view the emergence of basic stone flaking in the Oldowan as the first indications of our lineages burgeoning modernity. Oldowan stone knapping is a complex sensory motor task not shared by any other living species, and represents one of the first traceable steps towards modern cognition. We should look closer at the capabilities of the earliest Homo species which produced these tools. What can we gleam about the cognitive sophistication of these hominins which started the course of reasoning, spatial awareness, and ingenuity towards modernity?

7 UMASA Journal Volume 32 (2014) Alarie 7 Correlates of Oldowan Tool Use All humans are familiar with the use of tools and implements to overcome environmental limitations or anatomical limitations of our bodies. Tool use represents an extremely beneficial reaction to many physical pressures, and has helped our species exploit our environmental resources and protect against predation and interpersonal violence. With such a beneficial strategy so closely tied to subsistence, we would expect to find correlates of tool use in other closely related primate species. If correlates of tool use in other species can be found, what implications may this have for elucidating the evolution of tool use and human cognition? Extensive and flexible tool use has been defined by some as the hallmark of our species (Haslam et al 2009:339). However, several animal species have been observed using and creating tools of various forms and manipulating found objects or manuports (Haslam et al 2009:339). Detailed observation of wild African common chimpanzees has yielded evidence of habitual tool use and manufacture in our closest living primate relatives (Haslam et al 2009). Conversely, similar observation has yielded evidence of only infrequent tool use in bonobo chimpanzees (Haslam et al 2009:339). As a result of this observed variation, tool use among great apes and other primates has become one of the primary foci of primatology research. This new focus is predicated on the close relationship and shared evolutionary history of humans and other primates, great apes in particular (Haslam et al 2009:339). Evolutionary researchers have theorized, based on paleontological and genetic evidence, that our human linage split from the chimpanzee linage ~5-7 Myr (Haslam et al 2009:339). The earliest evidence of tool manufacture and production within the broad hominin lineage appears much later ~2.6 Myr with the Oldowan stone tool tradition (Haslam et al 2009:339). Most archaeologists argue that these earliest stone tools already show a marked degree of spatial coordination, planning depth, and manual dexterity, even though they were not produced by Homo sapiens. Haslam et al (2009:339) assert that earlier yet undiscovered stone tool traditions likely exist, and that there was more a gradually acquirement of ingenuity and skill before the Oldowan stone tools. Haslam et al (2009:339) pose the question that if tool production has been observed in both humans and chimpanzees, as well as in extinct hominins with chimpanzee sized brains, is it probable to assume that the common ancestor between humans and chimpanzees also produced tools? If so, can we use chimpanzees as a viable reference for early hominin tool use behaviour and cognition? Chimpanzee Analogy Comparative behavioural and cognitive studies among primate species have ushered in a new mode of information regarding the evolutionary and neurological origins of modern human tool making abilities. However, the legitimacy of the analogy between extinct hominin and chimpanzee cognition and tool use behaviour needs to be established. Researchers need to elucidate whether tool use in great apes and extinct hominins was independently evolved or whether tool production behaviour represents a continuum along these species. The sophisticated use and production of diverse stone tools has been long established in our human lineage, but is only a recent interest in primate evolutionary

8 UMASA Journal Volume 32 (2014) Alarie 8 studies (Cachel 2012:222). A key question to address is whether tool use in chimpanzees is a recent adaptation, or is their considerable antiquity of tool use in the chimpanzee evolutionary lineage? Primate researchers such as Haslam et al (2009:339) and Marchant et al (2012:191) cite the disconnect present between human evolutionary organic tool use did not occur until this time. However, given the existence of organic tool use in other primates, the poor preservation of organic materials, and the high malleability of organics, it is highly likely that organic tool use occurred much earlier than ~800 Kyr and may predate stone tool use (Haslam et al 2009:339). research and paleontological research as a significant barrier to resolving these questions. Recent work by Haslam et al (2009:339) has attempted to bridge this theoretical gap and establish this analogy through the compilation of a detailed archaeological record of chimpanzee stone tool use. Haslam et al (2009:339) assert that this new holistic approach of primate archaeology will provide a comparative framework for understanding the biological and environmental social contexts of primate behaviour through analyses of tool making, tool use, and spatially patterned accumulation of refuse. In light of this new approach researchers may be able to compare ancient great ape tool forms and landscape use with contemporary hominin assemblages (Marchant et al 2012:191). Haslam et al (2009:339) seek to reveal the behavioural and cognitive framework related to the evolution of stone tool use and manufacture in humans. As introduced previously, many wild primate species have been observed making and using tools from various organic and inorganic materials. Wild chimpanzees, orangutans, and capuchins have been noted to use wood, leaf, grass, and bark implements (Haslam et al 2009:339). Haslam et al (2009:339) posit that these observations of primate organic-tool use can help us bridge analogy and expand our current understanding of early hominin tool use behaviour. We do not find solid evidence of hominin organic tool use such as wood until ~800 Kyr, which may indicate that Primate Archaeology Due to the poor preservation of all organic materials through such a lengthy time depth, in both hominin and primate archaeology, there has been a heavy focus on well preserving inorganic stone tools and debitage. Stone tools and debris created by humans, hominins, and primates can be analysed in much of the same ways to elucidate landscape use, intentionality, skill, and cognition (Haslam et al 2009:340). Haslam et al (2009:339) assert that a significant amount of early hominin tool use history has been lost to time and poor preservation, but through the use of analogy we may be able to explore the likely development of stone tool production and use behaviours in hominins. Through a broad comparison of Oldowan stone tools and chimpanzee stone tools, a curious set of traits does emerge. Oldowan ( Myr) stone tool assemblages consist mainly of minimally worked cores, flakes, and associated debitage, however some Oldowan cores have been drastically reduced yielding numerous flakes (Toth et al 2009:289). Oldowan stone tools are characterized as non-symmetrically flaked and battered hammers or anvils (Toth et al 2009:289). It is theorized that these early tools were used to expose bone marrow and flesh for consumption (Toth et al 2009:289). Non-human observed examples of tool use

9 UMASA Journal Volume 32 (2014) Alarie 9 do not involve systematically producing flakes as in the Oldowan tradition, but they do share the hammer and anvil technique (Toth et al 2009:289). Chimpanzees have been observed using stone hammers and anvils to crack open hard-shelled nuts and fruits, while macaques have been noted to habitually use stone chimpanzees (Haslam et al 2009:342). This observation has reinforced the use of chimpanzee behaviour as analogy for early hominin tool use behaviour, and has also inspired numerous exploratory studies of nonhuman great ape cognitive and manual dexterity abilities (Toth et al 2009:289). implements to break open molluscs and crabs, and dig for tubers (Haslam et al 2009:340). These primate tooluse activities result in distinct abrasive, pitting, and fracture damage to the stone implements which have been observed in archaeological remains (Haslam et al 2009:341). The comparison between hominin and chimpanzee tool use is not identical, however it may shed light on the proto-flaking stage of hominin tool use. In addition, accidental anvil fracture during chimpanzee striking has been presented as a likely first step towards similar knapping behaviours in ancient hominins (Haslam et al 2009:341; Marchant et al 2011:181). Haslam et al (2009:341) posit that the origins of intentionally flaked implements may lie at the crossroads of primatology and archaeology, and that chimpanzee plant processing behaviours may lend significant insight into the first emergence of flaking innovation. Currently the Oldowan tool tradition is ascribed to the earliest Homo species, Homo habilis (~ Myr); however there are no directly associated remains to the Oldowan assemblages (Toth et al 2009:289). Given the already marked degree of complexity in the Oldowan stone tools in comparison to the manuport tool use of chimpanzees, Haslam et al (2009:341) posit that initial systematic stone flaking likely predates Homo habilis and is the innovation of the australopithecines. These australopithecines, who gave rise to early Homo, had relatively equivalent brain Can Non-Human Great Apes Knap? Several studies have been conducted to assess chimpanzee stone tool use and manufacturing abilities in an experimental setting. Chimpanzees have never been observed flint knapping in the wild. As a result, the aims of these studies were not to imply that chimpanzees employed human-like stone tool use and production. Instead, these studies attempted to demonstrate whether chimpanzees possessed the manual and cognitive capacities to learn knapping skills and the forethought to create situational specific tools. If chimpanzees can be taught to knap and demonstrate situation judgement, than we may infer that australopithecines of similar brain size, posture, and forelimb anatomy could also have produced the first flaked stone tools. Through a series of small scale experiments and long term teaching two sign language-competent bonobo chimpanzees, Kanzi and Pan-Banisha, were able to produce numerous flint knapped tools in a variety of tool classes (Roffman et al 2012: 1). In addition, Kanzi and Pan-Banisha were able to utilize these tools in situational specific contexts for food retrieval. During the 1990s both bonobos were taught to knap flint flakes by the Toth et al (2009) research team. Additionally, the bonobo pair was encouraged through hidden food rewards to use these flint flakes size and manual dexterity abilities to extant

10 UMASA Journal Volume 32 (2014) Alarie 10 to cut ropes and leather to retrieve the food stored in boxes and drums (Toth et al 2009:289). In these early studies, Toth et al (2009:290) observed that although the bonobos had demonstrated that they could produce stone tools and utilize them, they rarely resorted to these learned behaviours. Instead the researchers noted, that in most scenarios Kanzi and Pan-Banisha could accomplish the laid out task with their own brute strength or through using their teeth as cutting implements (Toth et al 2009:290). However, in experimental situations where anatomy could not accomplish food procurement both bonobos were observed knapping and using flakes to achieve their cutting goals (Toth et al 2009:290). Interestingly, Toth et al (2009:91) observed that the bonobos often hit their fingers while knapping, owing to the longer length of their digits compared to modern humans. This presented a frustrating and painful difficulty for the chimpanzees. As a result, the team often observed Kanzi creating quick cutting edges by throwing the raw cobbles at the ground with extreme force until they shattered, and then selecting suitable edges to use from the shatter. This feat requires strength in excess of a typical human s ability and could only be accomplished by a chimpanzee. Toth et al (2009:291) posit that this technique might have been a possible approach employed by early hominins with comparable body size and forelimb structure to chimpanzees. All of the stone tools created by Kanzi and Pan-Banisha were produced through direct percussion, whereby the core was held in the left hand and struck with the hammer stone held in the right hand (Roffman et al 2012:2). Both bonobos had learnt multiple knapping techniques through the Toth et al (2009) study, but appeared to favour this style likely due to its simplicity (Roffman et al 2012:2). Kanzi produced thick cortical flakes from the cores edge and small sharp flakes, While Pan-Banisha produced flakes of varying sizes with no thick cortical edge flakes (Roffman et al 2012:2). These two tool categories are very similar to the two Oldowan tools categories promoted by Leakey; the heavy-duty chopper/wedge-like tools and the light-duty scraper/drill-like tools. Roffman et al (2012:2) concluded through their subsequent study that both bonobos produced tools on a need basis and that tool form was influence by need. Critics of these earlier studies, cited that the experimental conditions were too far removed from any natural food procurement problem solving scenario that these bonobos would face in the wild (Roffman et al 2012:3). In subsequent studies conducted by Roffman et al (2012:3) Kanzi and Pan- Banisha were presented with two more likely food procurement tasks: breaking logs to obtain hidden food stores within, and digging for food hidden under rocks and sand. Both bonobos were provided a variety of materials including antler, sticks, and various stone cobbles. The bonobos were not guided or pressured to approach the logs and were given no time restraints (Roffman et al 2012:3). Roffman et al (2012:3) observed that Kanzi the male bonobo was able to break 24 logs, while Pan- Banisha was able to break only two logs. Kanzi used a myriad of approaches to break open the logs (Roffman et al 2012:3). He was observed prying at the log with antlers and sticks, striking the log on the ground, striking the log with another log, striking the log with an unmodified cobble, and was observed 60 times using modified stone tools to process the log (Roffman et al 2012:3). Throughout the duration of these trails Kanzi made and employed several stone tools:

11 UMASA Journal Volume 32 (2014) Alarie 11 chopper-like, drill-like, scraper-like, and small flakes and blade (Roffman et al 2012:3). In contrast, Pan- Banisha was only able to break open two logs by throwing them on the floor. She was observed using the antler, sticks, and some of Kanzi s tools attempting to open the logs with implements (Roffman et al 2012:3). Both Bonobos focused their efforts on the glue line of the log, where it was most vulnerable; however, Kanzi was much more successful (Roffman et al 2012:3). During the digging experiments, both bonobos chose tools according to soil hardness. They both used their hands in soft soil, used branches and antler in wet muddy soil, and used stone implements in hardened dry soil (Roffman et al 2012:3). Both bonobos used unmodified and modified stone tools to dig in the hard soil; however Pan-Banisha used modified stone tools 7 times more often than Kanzi (Roffman et al 2012:3). These studies demonstrate that chimpanzees can be taught to knap and incorporate modified stone tools as part of their daily problem solving tool-kit. We can also deduce that these non-human apes possess the cognitive abilities and dexterity to create flaked stone tools, even though it is not part of their observed wild behavioural repertoire. In another recent publication, researchers have observed the transmission of the learned knapping behaviours in both Kanzi and Pan-Banisha to their offspring through social rearing (Marchant et al 2012:191). So why did human and hominin population manufacture and use flaked stone tools, while chimpanzee populations did not? How does great ape cognition, in relation to making and using stone tools, differ from that of modern humans and extinct hominins? Is there something more significant than cognition restricting or influencing stone tool use behaviour in chimpanzees? Roffman et al (2012:3) observed the use-wear and cut marks left on the stone tools and logs, and compared the experimental signature produced by the two bonobos against the pattern observed in Oldowan assemblages. The team discovered that there was a significant similarity in use wear patterns between the bonobos and the hominins which produced the Oldowan assemblages. Roffman et al (2012:3-4) assert that chimpanzees are capable of creating and utilizing manuport stone tools as well as systematically flakes stone tools given an environmental situation which cannot be conquered through sheer anatomy or physical ability. Roffman et al (2012:3-4) strongly feel that chimpanzee stone tool use behaviour and cognitive capacity can be used as a strong analogy for the early hominin mental and physical condition. How do Humans and Great Apes Stack Up? As discussed earlier, stone tool use has been viewed as a hallmark of human cognition and modernity, however humans are not the only hominins or great apes to produce and use stone tools. It has been observed by many primatologists that living great ape species such as chimpanzees produce and use tools made from various materials, although it is generally accepted that these tools are simpler in form and function than human manufactured tools (Vaesen 2012:203; Roffman et al 2012:1; Haslam et al 2006:339). However, primate and human researchers disagree widely on the degree of complexity demonstrated in primate tool-kits and what cognitive abilities are shared between humans

12 UMASA Journal Volume 32 (2014) Alarie 12 and our closest living relatives (Vaesen 2012:203). In one human evolutionary theoretical camp researchers assert that humans possess higher reasoning and cognitive abilities, which alone allows humans to make and use more sophisticated tools (Vasesen 2012:203). In another camp, primatology researchers assert that great apes and humans share relatively similar cognitive and reasoning abilities or brainpower, but that it is humanity s greater social abilities such as imitation, teaching, and collaboration that attest to the greater complexity shown in human-made stone tools (Vaesen 2012:203). characteristics of humans which result in greater sociality, technological complexity, and high-fidelity cultural transmission. The author states that none of the eight identified cognitive traits is solely responsible for being the key differentiation between humans and other great apes, but that the whole suite of traits together is what constitutes our cognitive and social uniqueness (Vaesen 2012:203). Vaesen (2012:203) purports that this superior set of cognitive traits is a unique phylogenetic hallmark of Homo sapiens, and represents a significant cognitive departure or discontinuity from other great ape species. To test these assumptions of human and great ape mental complexity and the uniqueness of modern human cognition, Vaesen (2012: 203) performed a systematic neurological comparison of tool use among living great apes and humans. The author sought to determine whether human tool use demonstrated evidence of higher cognitive ability brainpower or whether humans and great apes share similar patterns of cognitive complexity and reasoning (Vaesen 2012: 203). Vaesen (2012:203) compared tool usage across nine categories of cognitive capacities she deemed critical for tool use; enhanced hand-eye coordination, body schema plasticity, causal reasoning, function representation, executive control, social learning, teaching, social intelligence, and language. Vaesen (2013:203) found that apes scored strikingly different than humans across eight of the nine categories, concluding that there was a significant degree of cognitive disparity evident between humans and extant great apes. The author concluded that humans possess a markedly greater capacity for reasoning, mental plasticity, functional representation, and communication (Vaesen 2012:211). Vaesen (2012:211) asserts that it is these superior cognitive Continuity or Discontinuity In a follow up article Gibson (2012:225) reinforces some of Vaesen s conclusions, and states that human technological complexity and sophistication greatly exceeds that expressed by other primates. Additionally, that this superior complexity is the result of a host of advanced interacting cognitive and motor skills and not the single action of one cognitive, motor, or social capacity (Gibson 2012:225). However, in regards to the potential for continuity of tool use from earlier hominids, humans, and great apes, Gibson (2012:225) prefers to make no assumptions. Gibson (2012:225) feels that perceptions of discontinuity or continuity in tool use behaviour and cognitive capabilities among extant and extinct great ape species, remains highly contentious. Gibson (2012:225) cites the observed trend of increased brain size throughout hominid evolution as a likely reference or map of cognitive continuity. On the other hand, Gibson (2012:225) does redress the marked cognitive disparity between humans and chimpanzees as significant evidence supporting discontinuity between extant

13 UMASA Journal Volume 32 (2014) Alarie 13 great apes and modern humans. Gibson (2012:225) further argues that discerning the source of human tool use behaviour and cognition is a multifaceted multidisciplinary problem, which cannot be resolved by focusing on just these nine aspects of tool use behaviour. In contrast, an article presented by Patterson and Mann (2012:235) asserts that cognitive processes such as the ones defined by Vaesen (2012) contribute to diversity and complexity in tool use behaviour, but they are not essential for tool use. Patterson and Mann (2012:235) feel that given the current evidence in neuroscience and behavioural biological, that tool use did not drastically shape the human pattern of cognitive development. The authors argue against the conclusion of coevolution of tool use and higher cognitive capabilities (Patterson and Mann 2012:236). In a response article to Vaesen s (2012) study, Blitzer and Huebner (2012: 221) argue that differences in human and great ape tool use behaviour do not stem solely from cognitive disparities, but rather are constrained by the vastly different relationships of living great apes and their environments. Blitzer and Huebner (2012:221) suggest that extant primates and great apes are subject to greatly different interactions with their physical environment, and that tool use behaviour is less a function of lower cognitive traits and more a function of environmental setting. The authors assert that human cognition evolved within a highly competitive ecological setting which has forced humans to act more dynamically within their environment, but ultimately having little impact on internal neurology in comparison to chimpanzees (Blitzer and Huebner 2012:222). Blitzer and Huebner (2012:222) feel that tool use and manufacture is more be placed on the great ape/hominid continuum of tool use and ecological reaction. In addition to this debate, Crabb (2012: 222) asserts that human capacities for tool use evolved through a set of different environmental selective pressures. Crabb (2012:222) theorizes a process of technological selection on the related neural architecture of ancestral hominids, due to their strict reliance on tools for their basic survival in a highly competitive ecological environment. Crabb ( ) asserts that early on in hominid evolution an individual s fitness was increased through use of tools to firstly ward of predation, secondly to procure subsistence, and thirdly in defence of food supplies in the volatile African Pleistocene climate. The author feels that it was the intensified subsequent use of stone tools by hominids which led to the greater cognitive complexities exhibited in humans in comparison to other tool-using apes (Crabb 2012:233). These researchers have come to vastly different interpretations of the driving force and context of cognitive evolution and tool use, but have been presented with the same body of evidence. This discussion has demonstrated that there are multiple, equally supported theories regarding the emergence and constitution of cognitive modernity. Furthermore, there remains much contention regarding the operational definitions of modernity and cognition which these interpretations are based upon. This variety of interpretation and disagreement is common in new and theoretical studies, however despite these differences a few common themes prevail the discussion. complex and sophisticated in humanity, but that it can

14 UMASA Journal Volume 32 (2014) Alarie 14 Conclusions Most researchers agree that stone tool use represents a significant milestone along the road to achieving human-like cognition. However, there remains considerable disagreement regarding which aspects of stone tool production and which tool traditions are the most cognitively significant. I tend to agree with researchers such as Bleed (2011:297), which have concluded that the ability to manage sequential activities and to move pragmatically through a series of decision points marks the most important development of the hominin mind eventually arising in cognitive modernity as we know it. Additionally, this new sequential reasoning likely occurred in context of with cranial growth and expansion of the motor cortex within our hominin lineage, which promoted the development of long-term memory capacity and high fidelity cultural transmission (Bleed 2011:297). I feel this ability of higher sequential reasoning is first expressed through the Oldowan stone tool tradition ~2.7 Myr. Researchers have shown that the producers of the Oldowan possess high cognitive capacity, as evidence by the strong activation of spatial reasoning areas of the brain while knapping Oldowan tools. A new area of research is now focusing on assessing the cognitive abilities of primates and great apes, and how they may relate to humans and extinct hominins. A significant degree of this work has aimed to establishing chimpanzee cognition and behaviour, as a useful analogy for early hominin behaviour and cognition. Researchers such as Wenban-Smith (2004) caution us to address our perspectives of comparison and anthropomorphic projection when we aim to reconstruct past behaviours of extinct hominins: When it comes to the behavioural interpretation of the archaeological evidence of extinct hominid species, one needs to be wary of incorporating it into patterns of behaviour that presume, and require, modern human cognitive capabilities. Thus the behavioural interpretation of any Lower/ Middle Palaeolithic archaeological evidence is contingent upon a perspective upon cognitive capabilities and the consequent potential style of adaptation (Wenban-Smith 2004:2-3). Nonetheless, researchers have observed that other primates, especially great apes, are capable of creating and using tools in a natural environment. Most specifically, chimpanzees have been observed creating a wide variety of organic and stone tools. However, these stone tools which comprise part of the chimpanzee natural repertoire are much simpler in form than humans and are not systematically flaked. Recent primate behavioural experiments have demonstrated that chimpanzees can be taught to knap Oldowan grade tools, and incorporate flaked stone tool use and manufacture into their daily problem solving tool-kits. Given this two conflicting avenues of information, we are left with a logical dilemma. We know stone tool use have been highly advantageous for humans and that chimpanzees possess the cognitive capacities to create and use flaked stone tools, however stone knapping has not become a natural part of their behavioural repertoire. Although both the earliest hominins and extant chimpanzees share many similarities in anatomy and brain size, their relationship with their environment were undoubtedly different. Much more research is

15 UMASA Journal Volume 32 (2014) Alarie 15 required to elucidate the evolutionary driver for increased spatial reasoning and stone tool production which influenced our hominin lineage and not the chimpanzee lineage. The scenario presented earlier by Blitzer and Huebner (2012) and Crabb (2012) is most probable given our current evidence. Early hominins likely evolved in a harsh and volatile climate, which selected for extremes of variations. Within such an environment ingenuity and tool use increased fitness. As a result, hominins gradually developed a more dynamic relationship with their environment than chimpanzee precursors. Over the millennia and through multiple hominin species, high cognition and technological complexity flourished; ultimately culminating presently with human cognitive modernity. Many of the interpretations of cognitive evolution are highly contentious, and there remains significant disagreement within the paleocognition research community. However, the field of paleocognition is both young and dynamic, and has only begun to systematically approach the question of the evolution of human cognition. Recent paleocognitive studies have been able to shed light on some major theoretical questions underpinning of view of modernity. References Cited Bleed, P Loosening Our Chaînes: Cognitive Insights for the Archaeological Application of Sequence Models. Paleo Anthropology, Special Issue: Reduction Sequence, Chaîne Opératoire, and Other Methods: The Epistemologies of Different Approaches to Lithic Analysis, SI: Blitzer, A., and Huebner, B Tool Use as Situated Cognition. Behavioural and Brain Sciences 35: Cachel, S Human Tool Behavior is Species- Specific and Remains Unique. Behavioural and Brain Sciences 35: 222. Crabb, P.B Technological Selection: A Missing Link. Behavioural and Brain Sciences 35: Darwin, C The Descent of Man: and Selection in Relation to Sex. London, UK: John Murray. Accessed via converted/pdf/1871_descent_f937.1.pdf, April 1, Foley, R., and Lahr, M.M On Stony Ground: Lithic Technology, Human Evolution, and the Emergence of Culture. Evolutionary Anthropology, Gibson, K Human Tool-Making Capacities Reflect Increased Information-Processing Capacities: Continuity Resides in the Eyes of the Beholder. Behavioural and Brain Sciences 35: Goren-Inbar, N Culture and Cognition in the Acheulean Industry: A Case Study from Gesher Benot Ya,aqov. Philosophical Transactions of the Royal Society of Biological sciences 366: Griffith, N.J.L Is Cognition Plus Technology an Unbounded System? Technology, Representation and Culture. Pragmatics & Cognition 13(3) Grove, M Speciation, Diversity, and Mode 1 Technologies: The Impact of Variability Selection. Journal of Human Evolution 61: