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Question one: Do flake attributes differ in morphospace size?
When do similarities in flake attributes reflect common cultural ancestry? Jonathan Paige, Charles Perreault Convergence is a potential problem in tracing cultural interactions in the Pleistocene Question two: Are attributes with smaller morphospaces more prone to convergence? Morphospace Attribute A Wider space Large coefficient of variation Greater potential for variation Methods Gathered flake data from two groups: Compared (KS-test) external platform angle (E), platform thickness (P) and length/width ratio (L) distributions between assemblages (315 comparisons). Similarities between Hohokam and outgroups counted as cases of convergence. Similarities within Hohokam, and differences between Hohokam and outgroup counted as successes. Archaeologists use similarities in flake attributes to infer cultural interaction, and migration (Tostevin 2012). However, flake similarities could be due to causes other than cultural interaction, or common cultural ancestry. How many possible forms a flake may take, or its morphospace (McGhee 2006), is constrained by the physics of fracture mechanics (Magnani et al. 2014, Moore 2011). Restricted morphospaces should be more prone to convergence: similar forms being made by chance by two groups without a cultural connection. Ingroups: Hohokam assemblages dating between A.D. recovered from Tonto Basin, Central Arizona. (N =620 flakes). Possible forms Outgroups: 13 experimental assemblages, and 5 old world Pleistocene assemblages (N=3,485 flakes). Attribute B Restricted space Small coefficient of variation Convergence is likely Impossible forms Question one: Do flake attributes differ in morphospace size? Methods Collected summary data on flakes (N=42,502) from 15 experimental and 51 archaeological assemblages. Assemblages span MP-UP Eurasia, Lomekwian-MSA Africa, late Holocene North America. Collected mean external platform angle (E), platform depth (P), and length:width ratios (L). Calculated coefficient of variation (CV) in each attribute as a proxy for relative size of morphospaces. Platform Thickness External platform angle Length: ratio Width Results Convergence more likely for external platform angle than other attributes Success in both identifying similarities among Hohokam, and differences between Hohokam and outgroup ranges between ~50% and ~70%. Results Attributes vary in size of morphospace (CV) Discussion Acknowledgements: Thanks to the researchers who published data used in this study, Derek Miltimore for the flake photo, Dr. Arleyn Simon, The Center for Archaeology and Society, and The Roosevelt Platform Mound Study for their help and access to the Tonto Basin assemblage. Attributes that have limited morphospaces should be more prone to convergence than other attributes. Outlining the morphospace for lithic technology is one way of exploring which attributes may be more or less useful for cultural reconstructions. Future studies will assess the scales at which different attributes retain cultural information. External platform angle (E) has the smallest CV, the most restricted morphospace, and should be most prone to convergence. Klassen, S., Harkness, R. (2015) EMAP Obsidian Flake Database (tDAR id: ) Magnani, M,. Rezek, Z., Lin, S., et al. (2014). Flake variation in relation to the application of force. Journal of Archaeological Science. McGhee, G. (2008). The Geometry of Evolution: Adaptive Landscapes and Theoretical Morphospaces. Cambridge University Press. Moore, M. W., & Perston, Y. (2016). Experimental Insights into the Cognitive Significance of Early Stone Tools. PloS one, 11(7), e Moore, M. (2011). The design space of stone flaking: implications for cognitive evolution. World Archaeology. (43)4, Munday, F. (1977). Nahal Aqev (D35): a stratified, open-air Mousterian occupation in the Avdat/Aqev area." Prehistory and paleoenvironments in the central Negev, Israel. Vol. 2. de la Peña, P. (2015). Refining Our Understanding of Howiesons Poort Lithic Technology: The Evidence from Grey Rocky Layer in Sibudu Cave (KwaZulu-Natal, South Africa). PloS one, 10(12), Bader, G., Will, M., Conrad, N. (2015). "The lithic technology of Holley Shelter, KwaZulu-Natal, and its place within the MSA of southern Africa." The South African Archaeological Bulletin, Cameron, J. (1985) Gran Quivira Limestone Lithic Database (tDAR id: ) Harmand, S., Lewis, J. E., Feibel, et al. (2015). 3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya. Nature, 521(7552), Hunstiger, M. (2016). Three Dimensional Aggregate Flake Scar Analysis and Hominin Behavior at Tabun Cave, Israel. Dissertation. Presnyakova, D., Archer, W., Braun, D. R., Flear, W. (2015). Documenting differences between early stone age flake production systems: An experimental model and archaeological verification. Plos one Tostevin, G. B. (2012). Seeing lithics. A Middle Range Theory for Testing for Cultural Transmission in the Pleistocene. American School of Prehistoric Research Monograph Series, Harvard.
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