TY - JOUR
T1 - Exploring variability in lithic armature discard in the archaeological record
AU - Gravel-Miguel, Claudine
AU - Murray, John K.
AU - Schoville, Benjamin J.
AU - Wren, Colin D.
AU - Marean, Curtis W.
N1 - Funding Information:
The authors recognize the support of a grant from the National Science Foundation ( BCS-1138073 ), Hyde Family Foundations , the Institute of Human Origins at Arizona State University, and the John Templeton Foundation to the Institute of Human Origins at Arizona State University. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of any of these funding organizations. Sincere thanks to Erik Otárola-Castillo (Department of Anthropology, Purdue University) for providing data on armature embedding/breaking rates, to Richard Cowling and Jan De Vynck (African Centre for Coastal Palaeoscience, Nelson Mandela University) for providing information on vegetation type cover, to the attendees of the Annual Meeting of the Paleoanthropology Society in Albuquerque who provided comments on the preliminary poster version of this article, and to the JHE reviewers, whose comments helped us improve this article.
Funding Information:
If the hunt is successful, the submodel identifies which body part was hit using probabilities determined from experimental work that quantified the frequency of hitting different body parts when aiming for the heart (Schoville et al., 2010). In turn, the body part hit affects the probability that the armature becomes embedded in the flesh of the animal or breaks on impact; these probabilities are also based on experimental work, where spear armatures were thrust into a deer carcass using a crossbow, and the damage created was recorded (Schoville et al., 2010; Wilkins et al., 2012; Schoville, 2016). If the armature breaks and is not embedded, it gets discarded onto the cell where the hunt took place. If the armature becomes embedded in the prey, a user-set probability (discussed below) affects the likelihood that it will be reused. Finally, the body part hit and the size of the prey affect the probability that an embedded armature that is not reused will be carried back to be discarded at the habitation camp. Prey of size 1 are transported whole to the habitation camp, along with any embedded armature. This decision is based on Hadza and !Kung hunting data (Yellen, 1991, p. 152; Monahan, 1998, p. 414), where the whole carcass of such small animals is usually transported back to the habitation camp. This is also supported by the assemblage of small mammals from MSA layers of Die Kelders 1, where most body parts are well represented, thus negating the idea that small mammals were butchered in the field (Armstrong, 2016). For prey of size 2, the probability that each body part gets carried back to the habitation camp (Table 3) is based on ethnographic observations (Bunn et al., 1988; O'Connell et al., 1988; Monahan, 1998; Schoville and Ot?rola-Castillo, 2014). These probabilities are not affected by the hunter's distance from camp because distance has been shown to have no significant impact on the body part transport for prey of size 2 and smaller (Schoville and Ot?rola-Castillo, 2014). When a hunter carries an embedded armature back to its habitation camp, the model transfers the armature's list of values to the cell where the camp stands.The authors recognize the support of a grant from the National Science Foundation (BCS-1138073), Hyde Family Foundations, the Institute of Human Origins at Arizona State University, and the John Templeton Foundation to the Institute of Human Origins at Arizona State University. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of any of these funding organizations. Sincere thanks to Erik Ot?rola-Castillo (Department of Anthropology, Purdue University) for providing data on armature embedding/breaking rates, to Richard Cowling and Jan De Vynck (African Centre for Coastal Palaeoscience, Nelson Mandela University) for providing information on vegetation type cover, to the attendees of the Annual Meeting of the Paleoanthropology Society in Albuquerque who provided comments on the preliminary poster version of this article, and to the JHE reviewers, whose comments helped us improve this article.
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/6
Y1 - 2021/6
N2 - The invention of projectile technology had important ramifications for hominin evolution. However, the number of stone points that could have been used as projectiles fluctuates in archaeological assemblages, making it difficult to define when projectile technology was first widely adopted and how its usage changed over time. Here we use an agent-based model to simulate a hunter-gatherer foraging system where armatures are dropped according to their usage. We explore the impact of interactions between human behaviors and the environmental constraints of a data-informed landscape on the distribution and number of lithic armatures found in archaeological assemblages. We ran 2400 simulations modeling different population sizes, rates of hunting with projectiles, and tool curation levels. For each simulation, we recorded the location of dropped armatures and calculated the number and percentage of used armatures that were discarded at habitation camps vs. lost during hunting. We used linear regression to identify the demographic, behavioral, and environmental factor(s) that best explained changes in these numbers and percentages. The model results show that in a well-controlled environment, most armatures used as projectile weapons are lost or discarded at hunting sites; only ∼4.5% of used armatures (or ∼2 armatures per year of simulation) are discarded in habitation camps where they would likely be excavated. These findings suggest that even rare hafted armatures found in the Early and Middle Stone Age could indicate a well-established use of such tools. Our model shows that interactions between reoccupation of archaeological sites, population size, rate of hunting with projectile weapons, and tool curation levels strongly influence the count of lithic armatures found in archaeological assemblages. Therefore, we argue that fluctuations in the counts of armatures documented at archaeological sites should be evaluated within their demographic and environmental contexts to better understand if they reflect spatiotemporal changes in hunting behavior.
AB - The invention of projectile technology had important ramifications for hominin evolution. However, the number of stone points that could have been used as projectiles fluctuates in archaeological assemblages, making it difficult to define when projectile technology was first widely adopted and how its usage changed over time. Here we use an agent-based model to simulate a hunter-gatherer foraging system where armatures are dropped according to their usage. We explore the impact of interactions between human behaviors and the environmental constraints of a data-informed landscape on the distribution and number of lithic armatures found in archaeological assemblages. We ran 2400 simulations modeling different population sizes, rates of hunting with projectiles, and tool curation levels. For each simulation, we recorded the location of dropped armatures and calculated the number and percentage of used armatures that were discarded at habitation camps vs. lost during hunting. We used linear regression to identify the demographic, behavioral, and environmental factor(s) that best explained changes in these numbers and percentages. The model results show that in a well-controlled environment, most armatures used as projectile weapons are lost or discarded at hunting sites; only ∼4.5% of used armatures (or ∼2 armatures per year of simulation) are discarded in habitation camps where they would likely be excavated. These findings suggest that even rare hafted armatures found in the Early and Middle Stone Age could indicate a well-established use of such tools. Our model shows that interactions between reoccupation of archaeological sites, population size, rate of hunting with projectile weapons, and tool curation levels strongly influence the count of lithic armatures found in archaeological assemblages. Therefore, we argue that fluctuations in the counts of armatures documented at archaeological sites should be evaluated within their demographic and environmental contexts to better understand if they reflect spatiotemporal changes in hunting behavior.
KW - Agent-based model
KW - Hunter-gatherers
KW - Middle Stone Age
KW - Paleoscape model
KW - Projectile armatures
KW - South Africa
UR - http://www.scopus.com/inward/record.url?scp=85103934813&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85103934813&partnerID=8YFLogxK
U2 - 10.1016/j.jhevol.2021.102981
DO - 10.1016/j.jhevol.2021.102981
M3 - Article
C2 - 33848696
AN - SCOPUS:85103934813
SN - 0047-2484
VL - 155
JO - Journal of human evolution
JF - Journal of human evolution
M1 - 102981
ER -