Early Hominin Paleoecology

9. The Behavior of Plio-Pleistocene Hominins

325 9 The Behavior of PlioPleistocene Hominins: Archaeological Perspectives David R. Braun The ecology of early Pleistocene hominins (members of the human clade; Wood and Richmond 2000) is a complicated relationship between cultural mechanisms and biological adaptations. Although skeletal remains of hominins represent the most concrete evidence of human evolution, the archaeological record is the most abundant record of the ecology of our ancestors . The relatively large amount of stone artifacts and associated animal bones allows archaeologists to view hominin behavior through time and across ancient landscapes. The combination of time transgressive (across time periods at one location) and synchronic (across one time horizon at many locations) approaches is unique to an archaeological perspective.It also allows us to ask questions about behavior that can act as independent lines of evidence to compare and contrast with skeletal evidence of hominin evolution. The period between 2.6 to 1.6 mya (million years ago) was a crucial time in the history of human evolution . The archaeological assemblages associated within this time horizon are often termed the Oldowan after the site of Olduvai Gorge in Tanzaniza (Leakey 1967, 1971). This period hosted the first appearance of chipped-stone artifacts (Semaw 2000; Semaw et al. 1997).A recent report suggests that hominins may have accessed animal resources (meat and marrow) even earlier than this (~3.4 mya; McPherron et al. 2010), possibly with naturally sharp stones (but see DominguezRodrigo et al. 2010). Evidence of hominins butchering DOI: 10.5876/9781607322252:c09 david r. braun 326 large mammals prior to 2.0 mya exists in the Afar, yet this evidence is infrequent and currently poorly documented (de Heinzelin et al. 1999; DomínguezRodrigo et al. 2005; Domínguez-Rodrigo 2009). These major shifts in hominin behavior have implications for the nature and timing of hominin dietary changes (Blumenschine 1987; Blumenschine et al. 1991; Dominguez-Rodrigo and Pickering 2003), the interrelationship of behavioral and environmental variability through time (Potts 1998), and even the eventual global distribution of the genus Homo (Antón et al. 2002). The archaeological record represents a snapshot of decisions made by hominins to acquire resources necessary for their survival. We may even be able to investigate hominin cognitive development independent of biological changes in the hominin brain (Stout et al.2000; Stout 2002; Stout and Chaminade 2009). However, all high-order models of hominin behavior are based on very meager evidence. Despite the volume of material that represents the early Pleistocene archaeological record, it is after all just broken rocks and bones.We extrapolate hypotheses about hominin behavior from what we think are the processes that produced the archaeological record. Continued examination of every inferential step between the battered cobbles and hypotheses about hominin behavioral variation is a vital aspect of the archaeology of human origins (Braun et al. 2006). The aim of this chapter is to investigate how we “know” what we think we know about early Pleistocene hominin behavior by reviewing studies that focus on archaeological collections from 2.6 to 1.9 mya. The last three decades of research have provided archaeologists with large collections of shattered rocks and fossilized bones that were collected in a controlled manner from deposits of known geological age. Thus archaeologists now have the collections needed to begin to test hypotheses about how hominins made a living. Almost all of the evidence derives from two major proxies of human behavior and their associated specialized fields of analysis: stone tools (lithic analysis) and fossil animal bones (zooarchaeological analysis). These two fields are unfortunately rarely integrated (although see Brantingham 1998 for one attempt),despite the clearly complementary nature of these two proxies of behavior. HOMININ TRACE FOSSILS Stone artifacts and bones with evidence of hominin butchery represent traces of hominins that can answer particular questions about the behavior of our ancestors. Lithic and zooarchaeological analyses can be distilled down to a few main questions. Lithic analysts study stone artifacts to determine (1) how and the behavior of plio-pleistocene hominins 327 why hominins collected stones, (2) why they broke stones to make sharp edges in particular patterns, (3) why they used certain stones for certain tasks (if they did), and (4) how and why they decided to drop broken stones in particular places. In a similar fashion zooarchaeologists study bones to understand (1) which parts of mammal carcasses were accessed by hominins, (2) where and under what ecological conditions hominins gained access to...