Skip to main content
×
×
Home

The Social Consequences of Climate Change in the Central Mesa Verde Region

  • Dylan M. Schwindt (a1), R. Kyle Bocinsky (a2), Scott G. Ortman (a3), Donna M. Glowacki (a4), Mark D. Varien (a1) and Timothy A. Kohler (a2)...
Abstract

The consequences of climate change vary over space and time. Effective studies of human responses to climatically induced environmental change must therefore sample the environmental diversity experienced by specific societies. We reconstruct population histories from A.D. 600 to 1280 in six environmentally distinct portions of the central Mesa Verde region in southwestern Colorado, relating these to climate-driven changes in agricultural potential. In all but one subregion, increases in maize-niche size led to increases in population size. Maize-niche size is also positively correlated with regional estimates of birth rates. High birth rates continued to accompany high population levels even as productive conditions declined in the A.D. 1200s. We reconstruct prominent imbalances between the maize-niche size and population densities in two subregions from A.D. 1140 to 1180 and from A.D. 1225 to 1260. We propose that human responses in those subregions, beginning by the mid-A.D. 1200s, contributed to violence and social collapse across the entire society. Our findings are relevant to discussions of how climate change will affect contemporary societies.

Las consecuencias del cambio climático varían a través del tiempo y espacio. Por lo tanto, estudios efectivos de las respuestas humanas al cambio ambiental climáticamente inducido tienen que muestrear la diversidad ambiental experimentada por sociedades específicas. Nosotros reconstruimos historias poblacionales desde 600 hasta 1.200 d.C. en seis porciones ambientalmente distintas de la región central de Mesa Verde, en el suroeste de Colorado, relacionándolas con cambios climáticamente inducidos en el potencial agrícola. En todas menos una de las subregiones, aumentos en la extensión del nicho del maíz llevaron a incrementos en el tamaño poblacional. La extensión del nichodel maíz también está positivamente correlacionada con estimociones regionales de tasas de natalidad. Las altas tasas de natalidad continuaron acompañando altos niveles poblacionales aún cuando las condiciones productivas declinaron en el 1.200 d.C. Nosotros reconstruimos desbalances destacados entre el tamaño del nicho del maíz y las densidades poblacionales en dos subregiones desde 1.140 a 1.180 años d.C. y desde 1.225 a 1.260 años d.C. Proponemos que, comenzando a mediados del 1.200 d.C., las respuestas humanas en estas subregiones contribuyeron a la violencia y al colapso social a través de toda la sociedad. Nuestros hallazgos son relevantes para las discusiones acerca de cómo el cambio climático afectará a las sociedades contemporáneas.

Copyright
Corresponding author
(tako@wsu.edu)
References
Hide All
Adams, Karen A., and Petersen, Kenneth L. 1999 Environment. In Colorado Prehistory: A Context for the Southern Colorado River Basin, edited by William D. Lipe, Mark D. Varien, and Richard H. Wilshusen, pp. 1450. Colorado Council of Professional Archaeologists, Denver, Colorado.
Adler, Michael A. 1994 Population Aggregation and the Anasazi Social Landscape: A View from the Four Corners. In The Ancient Southwestern Community: Models and Methods for the Study of Prehistoric Social Organization, edited by W. H. Wills and Robert D. Leonard, pp. 85101. University of New Mexico Press, Albuquerque.
Adler, Michael A. 1996 Land Tenure, Archaeology, and the Ancestral Pueblo Social Landscape. Journal of Anthropological Archaeology 15:337371.
Baxter, Michael 2003 Statistics in Archaeology. Arnold, London.
Bellorado, Benjamin 2007 Breaking Down the Models: Reconstruction Prehistoric Subsistence Agriculture in the Durango District of Southwestern Colorado. Unpublished Master's thesis, Department of Anthropology, Northern Arizona University, Flagstaff.
Benson, Larry V. 2011a Factors Controlling Pre-Columbian and Early Historic Maize Productivity in the American Southwest, Part 1: The Southern Colorado Plateau and Rio Grande Regions. Journal of Archaeological Method and Theory 18:160.
Benson, Larry V. 2011b Factors Controlling Pre-Columbian and Early Historic Maize Productivity in the American Southwest, Part 2: The Chaco Halo, Mesa Verde, Pajarito Plateau/Bandelier, and Zuni Archaeological Regions. Journal of Archaeological Method and Theory 18:61109.
Benson, Larry V., and Berry, Michael S. 2009 Climate Change and Cultural Response in the Prehistoric American Southwest. Kiva 75:89119.
Billman, Brian R. 2003 The Puebloan Occupation of the lite Mountain Piedmont: Volume 7: Synthesis and Conclusions. Soil Systems Publications in Archaeology, No. 22. Phoenix, Arizona.
Billman, Brian R., Lambert, Patricia M., and Leonard, Banks L. 2000 Cannibalism, Warfare, and Drought in the Mesa Verde Region during the Twelfth Century A.D. American Antiquity 65:145178.
Bocinsky, R. Kyle, and Kohler, Timothy A. 2014 A 2000-Year Reconstruction of the Rain-Fed Maize Agricultural Niche in the US Southwest. Nature Communications 5:5618. DOI: 10.1038/ncomms6618.
Bradley, Bruce A. 1993 Planning, Growth, and Functional Differentiation at a Prehistoric Pueblo: A Case Study from SW Colorado. Journal of Field Archaeology 20:2342.
Bretemitz, David A., Robinson, Christine K., and Timothy Gross, G. (compilers) 1986 Dolores Archaeological Program: Final Synthetic Report. Bureau of Reclamation, Engineering and Research Center, Denver.
Chenault, Mark L. (editor) 1996 Settlement Patterns in the Mancos and La Plata River Basins: A Class 2 Cultural Resource Survey for the Animas-La Plata Project. SWCA Environmental Consultants.
Cook, Benjamin I., Ault, Toby R., and Smerdon, Jason E. 2015 Unprecedented 21st Century Drought Risk in the American Southwest and Central Plains. Science Advances DOI: 10.1126/sciadv.l40O082.
Cowgill, George L, 1975 On Causes and Consequences of Ancient and Modern Population Changes. American Anthropologist 77:505525.
Daly, Christopher, Halbleib, Michael, Smith, Joseph I., Gibson, Wayne P., Doggett, Matthew K., Taylor, George H., Curtis, Jan, and Pasteris, Phillip A. 2008 Physiographically Sensitive Mapping of Climatological Temperature and Precipitation across the Conterminous United States. International Journal of Climatology 28:20312064.
Dettling, Lisa J., and Kearney, Melissa Schettini 2011 House Prices and Birth Rates: The Impact of the Real Estate Market on the Decision to Have a Baby. Working Paper 17485, National Bureau of Economic Research, Cambridge, Massachusetts. Electronic document, http://www.nber.org/papers/w 17485, accessed November 18, 2015.
Diamond, Jared 2005 Collapse: How Societies Choose to Fail or Succeed. Viking, New York.
Doelle, William H. 2000 Tonto Basin Demography in a Regional Perspective. In Salado, edited by Jeffrey S. Dean, pp. 81105. Amerind Foundation New World Studies Series No. 4. Amerind Foundation, Dragoon, Arizona, and University of New Mexico Press, Albuquerque.
Douglass, A. E. 1929 The Secret of the Southwest Solved by Talkative Tree Rings. National Geographic 54:737770.
Douglass, A. E. 1946 Precision of Ring Dating in Tree-Ring Chronologies. Laboratory of Tree-ring Research 3:321.
Downey, Sean S., Bocaege, Emmy, Kerig, Tim, Edinborough, Kevan, and Shennan, Stephen 2014 The Neolithic Demographic Transition in Europe: Correlation with Juvenility Index Supports Interpretation of the Summed Calibrated Radiocarbon Date Probability Distribution (SCDPD) as a Valid Demographic Proxy. PLoS ONE 9(8):el05730.
Foster, William C. 2012 Climate and Culture Change in North America AD 900–1600. University of Texas Press, Austin.
Gilmore, Kevin P., and Larmore, Sean 2012 Looking for Lovitt in All the Wrong Places: Migration Models and the Athabaskan Diaspora as Viewed from Eastern Colorado. In From the Land of Ever Winter to the American Southwest: Athabaskan Migrations, Mobility andEthnogenesis, edited by Deni J. Seymour, pp. 3777. University of Utah Press, Salt Lake City.
Glowacki, Donna M. 2012 The Mesa Verde Community Center Survey: Documenting Large Pueblo Villages in Mesa Verde National Park, Report on file, Mesa Verde National Park, Colorado.
Glowacki, Donna M. 2015 Living and Leaving: A Social History of Regional Depopulation in Thirteenth-Century Mesa Verde. University of Arizona Press, Tucson.
Glowacki, Donna M., and Ortman, Scott G. 2012 Characterizing Community Center (Village) Formation in the VEP Study Area, A.D. 600–1280. In Emergence and Collapse of Early Villages: Models of Central Mesa Verde Archaeology, edited by Timothy A. Kohler and Mark D. Varien, pp. 219246. University of California Press, Berkeley.
Grissino-Mayer, Henri D., and Fritts, Harold C. 1997 The International Tree-Ring Data Bank: An Enhanced Global Database Serving the Global Scientific Community. The Holocene 7:235238.
Hayes, Alden C. 1964 The Archaeological Survey of Wetherill Mesa, Mesa Verde National Park – Colorado. Archaeological Research Series Number 7A. National Park Service, U.S. Department of the Interior, Washington, D.C.
Hegmon, Michelle, Ortman, Scott G., and Mobley-Tanaka, Jeannette L. 1999 Women, Men, and the Organization of Space. In Women and Men in the Prehispanic Southwest: Labor, Power, and Prestige, edited by Patricia L. Crown, pp. 4390. School for American Research Press, Santa Fe.
Hegmon, Michelle, Peeples, Matthew A., Kinzig, Ann P., Kulow, Stephanie, Meeghan, Cathryn M., and Nelson, Margaret C. 2008 Social Transformation and Its Human Costs in the Prehispanic U.S. Southwest. American Anthropologist 110:313324.
Hsiang, Solomon M., Burke, Marshall, and Miguel, Edward 2013 Quantifying the Influence of Climate on Human Conflict. Science 341: DOI: 10.1126/science.l235367.
Ives, John W. 2014 Resolving the Promontory Culture Enigma. In Archaeology in the Great Basin and Southwest: Papers in Honor of Don D. Fowler, edited by Nancy J. Parezo and Joel C. Janetski, pp. 149162. University of Utah Press, Salt Lake City.
Ives, John W., Froese, Duane G., Janetski, Joel C., Brock, Fiona, and Ramsey, Christopher Bronk 2014 A High Resolution Chronology for Steward's Promontory Culture Collections, Promontory Point, Utah. American Antiquity 79:616637.
Johnson, C. David, Kohler, Timothy A., and Cowan, Jason 2005 Modeling Historical Ecology, Thinking about Contemporary Systems. American Anthropologist 107:96107.
Kelley, Colin P., Mohtadi, Shahrzad, Cane, Mark A., Seager, Richard, and Kushnir, Yochanan 2015 Climate Change in the Fertile Crescent and Implications of the Recent Syrian Drought. Proceedings of the National Academy of Sciences 112:32413246.
Kintigh, Keith W., Altschul, Jeffrey H., Beaudry, Mary C., Drennan, Robert D., Kinzig, Ann P., Kohler, Timothy A., Fredrick Limp, W., Maschner, Herbert D.G., Michener, William K., Pauketat, Timothy R., Peregrine, Peter, Sabloff, Jeremy A., Wilkinson, Tony J., Wright, Henry T., and Zeder, Melinda A. 2014 Forum: Grand Challenges for Archaeology. American Antiquity 79:524.
Kleidon, Jim, Diederichs, Shanna, and Glowacki, Donna M. 2007 Long Mesa 2002 Fire Burned Area Archeological Inventory, Mesa Verde National Park, Colorado: Puebloan Settlement, Demographics, and Community Structure, A.D. 500–1300 on Chapin and Park Mesas. Division of Research and Resource Management, Mesa Verde National Park, Colorado.
Kleidon, Jim, Hendrix, Michael, Long, Dani, Payne, Sarah, Rezac, Ed, Shanks, Bryan, Diederichs, Shanna, Karchut, Jeremy, Macmillan, Vince, and Beezley, John 2003 Bircher-Pony Post Fire Assessment Project (Two Volumes and Appendix). U.S. Department of the Interior, National Park Service, Mesa Verde National Park, Colorado.
Kohler, Timothy A. 2012 Modeling Agricultural Productivity and Farming Effort. In Emergence and Collapse of Early Villages: Models of Central Mesa Verde Archaeology, edited by Timothy A. Kohler and Mark D. Varien, pp. 7384. University of California Press, Berkeley.
Kohler, Timothy A., Crabtree, Stefani A., Kyle Bocinsky, R., and Hooper, Paul L. 2015 Sociopolitical Evolution in Midrange Societies: The Prehispanic Pueblo Case. Santa Fe Institute Working Paper 15-04-011. Electronic document, http://www.santafe.edu/media/workingpapers/15-04-011.pdf, accessed April 15, 2015.
Kohler, Timothy A., and Reese, Kelsey M. 2014 Long and Spatially Variable Neolithic Demographic Transition in the North American Southwest. Proceedings of the National Academy of Sciences 111:1010110106.
Kohler, Timothy A., Oilman, Scott G., Grundtisch, Katie E., Fitzpatrick, Carly, and Cole, Sarah M. 2014 The Better Angels of Their Nature: Declining Violence through Time among Prehispanic Farmers of the Pueblo Southwest. American Antiquity 79:444464.
Kohler, Timothy A., and Varien, Mark D. (editors) 2012 Emergence and Collapse of Early Villages: Models of Central Mesa Verde Archaeology. University of California Press, Berkeley.
Kohler, Timothy A., Varien, Mark D., and Wright, Aaron M. (editors) 2010 Leaving Mesa Verde: Peril and Change in the Thirteenth-Century Southwest. University of Arizona Press, Tucson.
Kolm, Kenneth E., and Smith, Schaun M. 2012 Modeling Paleohydrological System Structure and Function. In Emergence and Collapse of Early Villages: Models of Central Mesa Verde Archaeology, edited by Timothy A. Kohler and Mark D. Varien, pp. 7384. University of California Press, Berkeley.
Kuckelman, Kristin A. 2010 The Depopulation of Sand Canyon Pueblo, a Large Ancestral Pueblo Village in Southwestern Colorado. American Antiquity 75:497526.
Kuckelman, Kristin A. (editor) 2000 The Archaeology of Castle Rock Pueblo: A Thirteenth-Century Village in Southwestern Colorado. Electronic document, www.crowcanyon.org/castlerock, accessed October 21,2014.
Kuckelman, Kristin A., Coffey, Grant D., and Copeland, Steven R. 2009 Interim Descriptive Report of Research at Goodman Point Pueblo (Site 5MT604), Montezuma County, Colorado, 2005–2008 [PDF Title]. Electronic document, http://www.crowcanyon.org/goodmanpoint2005_2008, accessed April 6, 2015.
Kuckelman, Kristin A., Lightfoot, Ricky R., and Martin, Debra L. 2002 The Bioarchaeology and Taphonomy of Violence at Castle Rock and Sand Canyon Pueblos, Southwestern Colorado. American Antiquity 67:486513.
Laland, Kevin N., and O'Brien, Michael J. 2010 Niche Construction Theory and Archaeology. Journal of Archaeological Method and Theory 17:303322.
Lekson, Stephen H. 1988 The Idea of the Kiva in Anasazi Archaeology. Kiva 53:213234.
Lightfoot, Ricky R. 1994 The Duckfoot Site, Volume 2: Archaeology of the House and Household. Occasional Papers, No. 4. Crow Canyon Archaeological Center, Cortez, Colorado.
Lipe, William D. 1989 Social Scale of Mesa Verde Anasazi Kivas. In The Architecture of Social Integration in Prehistoric Pueblos, edited by William D. Lipe and Michelle Hegmon, pp. 5371. Occasional Papers, no. 1. Crow Canyon Archaeological Center, Cortez, Colorado.
Lipe, William D. 1995 The Depopulation of the Northern San Juan: Conditions in the Turbulent 1200s. Journal of Anthropological Archaeology 14:143169.
Lipe, William D., and Ortman, Scott G. 2000 Spatial Patterning in Northern San Juan Villages, A.D. 1050–1300. Kiva 66:91122.
Lister, Florence C. 2004 Troweling Through Time. University of New Mexico Press, Albuquerque.
Matson, R. G. 2015 The Nutritional Context of Pueblo III Depopulation of the Northern San Juan: Too Much Maize? Journal of Archaeological Science: Reports http://dx.doi.org/10.1016/j.jasrep.2015.08.032.
Mills, Barbara J., Clark, Jeffery J., Peeples, Matthew A., Haas, Jr., Roberts, John M. Jr., Brett Hill, W. R., Huntley, Deborah L., Borck, Lewis, Breiger, Ronald L., Clauset, Aaron, and Steven Shackley, M. 2013 Transformation of Social Networks in the Late Pre-Hispanic US Southwest. Proceedings of the National Academy of Sciences 110:57855790.
Morris, Earl H. 1919 Preliminary Account of the Antiquities of the Region Between the Mancos and La Plata Rivers in Southwestern Colorado. In Thirty-Third Annual Report of the Bureau of American Ethnology, 1911–1912, pp. 155205. Smithsonian Institution, Washington, D.C.
Nelson, Ben A., Martin, Debra L., Swedlund, Alan C., Fish, Paul R., and Armelagos, George J. 1994 Studies in Disruption: Demography and Health in Prehistoric American Southwest. In Understanding Complexity in the Prehistoric Southwest, edited by George J. Gumerman and Murray Gell-Mann, pp. 59112. Santa Fe Institute Studies in the Sciences of Complexity Proceedings XVI. Addison-Wesley, Reading, Massachusetts.
Nickens, Paul 1981 Pueblo III Communities in Transition: Environment and Adaptation in Johnson Canyon. Colorado Archaeological Society, Boulder.
Ortman, Scott G. 2012 Winds from the North: Tewa Origins and Historical Anthropology. University of Utah Press, Salt Lake City.
Ortman, Scott G. 2014 Uniform Probability Density Analysis and Population History in the Tewa Basin, New Mexico. Journal of Archaeological Method and Theory 21:132.
Ortman, Scott G., Glowacki, Donna M., Varien, Mark D., and David Johnson, C. 2012 The Study Area and the Ancestral Pueblo Occupation. In Emergence and Collapse of Early Villages: Models of Central Mesa Verde Archaeology, edited by Timothy A. Kohler and Mark D. Varien, pp. 1540), University of California Press, Berkeley.
Ortman, Scott G., Varien, Mark D., and Lee Gripp, T. 2007 Empirical Bayesian Methods for Archaeological Survey Data: An Application from the Mesa Verde Region. American Antiquity 72:241272.
Reed, Erik 1958 Excavations in Mancos Canyon, Colorado. University of Utah Press, Salt Lake City.
Rohn, Arthur H. 1965 Postulation of Socio-Economic Groups from Archaeological Evidence. In Contributions of the Wetherill Mesa Archaeological Project, edited by Douglas Osborne, pp. 6569. Memoir No. 19. Society for American Archaeology, Washington, D.C.
Rohn, Arthur H. 1977 Cultural Change and Continuity on Chapin Mesa. Regents Press of Kansas, Lawrence.
Rohn, Arthur H. 1989 Northern San Juan Prehistory. In Dynamics of Southwest Prehistory, edited by Linda S. Cordell and George J. Gumerman, pp. 149177. Smithsonian Institution Press, Washington, D.C.
Sahlins, Marshall D. 1972 Stone Age Economics. Aldine, Chicago.
Shennan, Stephen 2002 Genes, Memes and Human History: Darwinian Archaeology and Cultural Evolution. Thames & Hudson, London.
Shennan, Stephen, Downey, Sean S., Timpson, Adrian, Edinborough, Kevan, Colledge, Sue, Kerig, Tim, Manning, Katie, and Thomas, Mark G. 2013 Regional Population Collapse Followed Initial Agriculture Booms in Mrd-Holocene Europe. Nature Communications 4:2486. DOI: 10.1038/ncomms3486.
Stahle, David W., Cleaveland, Malcolm K., Grissino-Mayer, Henri D., Daniel Griffin, R., Fye, Falko K., Therrell, Matthew D., Bumette, Dorian J., Meko, David M., and Diaz, Jose Villanueva 2009 Cool- and Warm-Season Precipitation Reconstructions over Western New Mexico. Journal of Climate 22:37293750.
Thompson, Ian 1993 The Towers of Hovenweep. Mesa Verde Museum Association, Mesa Verde, Colorado.
Till, Jonathan D. 2012 Ceramic Analysis of Selected Sherd Collections from Hovenweep National Monument, 2012. Abajo Archaeology. Manuscript on file, Crow Canyon Archaeological Center, Cortez, Colorado.
Till, Jonathan D. 2014 Analysis of Pottery Collections from Hovenweep National Monument, Results from Year 2. Abajo Archaeology. Manuscript on file, Crow Canyon Archaeological Center, Cortez, Colorado.
Trawick, Paul, and Hornborg, Alf 2015 Revisiting the Image of Limited Good: On Sustainability, Thermodynamics, and the Illusion of Creating Wealth. Current Anthropology 56:127.
Turner, Brian L. II, and Sabloff, Jeremy A. 2012 Classic Period Collapse of the Central Maya Lowlands: Insights about Human-Environment Relationships for Sustainability. Proceedings of the National Academy of Sciences 109:1390813914.
van der Leeuw, Sander E., and Redman, Charles L. 2002 Placing Archaeology at the Center of Environmental Studies. American Antiquity 67:597605.
Van West, Carla R. 1994 Modeling Prehistoric Agricultural Productivity in Southwestern Colorado: A GIS Approach. Reports of In vestigations No. 67. Department of Anthropology, Washington State University, Pullman, and Crow Canyon Archaeological Center, Cortez, Colorado.
Varien, Mark, D. 1999 Sedentism and Mobility in a Social Landscape: Mesa Verde and Beyond. University of Arizona Press, Tucson.
Varien, Mark, D. 2000 Introduction. Kiva 66:518.
Varien, Mark D., Ortman, Scott G., Kohler, Timothy A., Glowacki, Donna M., and David Johnson, C. 2007 Historical Ecology in the Mesa Verde Region: Results from the Village Project. American Antiquity 72:273300.
Varien, Mark D., and Wilshusen, Richard H. 2002 A Partnership for Understanding the Past: Crow Canyon Research in the Central Mesa Verde Region. In Seeking the Center Place: Archaeology and Ancient Communities in the Mesa Verde Region, edited by Mark D. Varien and Richard H. Wilshusen, pp. 323. University of Utah Press, Salt Lake City.
Warner, Koko, Hamza, Mohamed, Oliver-Smith, Anthony, Renaud, Fabrice, and Julca, Alex 2010 Climate Change, Environmental Degradation and Migration. Natural Hazards 55:689715.
White, Tim D. 1992 Prehistoric Cannibalism at Mancos 5MTUMR-2346. Princeton University Press, Princeton.
Wilshusen, Richard H. 2002 Estimating Population in the Central Mesa Verde Region. In Seeking the Center Place: Archaeology and Ancient Communities in the Mesa Verde Region, edited by Mark D. Varien and Richard H. Wilshusen, pp. 101120. University of Utah Press, Salt Lake City.
Wilshusen, Richard H., and Blinman, Eric 1992 Pueblo I Village Formation: A Reevaluation of Sites Recorded by Earl Morris on Ute Mountain Ute Tribal Lands. Kiva 57:251269.
Wilshusen, Richard H., Ortman, Scott G., Diederichs, Shanna, Glowacki, Donna M., and Coffey, Grant 2012 Heartland of the Early Pueblos: The Central Mesa Verde. In Crucible of Pueblos: The Early Pueblo Period in the Northern Southwest, edited by Richard H. Wilshusen, Gregson Schachner, and James R. Allison, pp. 1434. Monograph 71, Cotsen Institute of Archaeology Press, University of California, Los Angeles.
Wilson, C. Dean, and Blinman, Eric 1988 Identification of Non-Mesa Verde Ceramics in Dolores Archaeological Program Collections. In Dolores Archaeological Program: Supporting Studies: Additive and Reductive Technologies, edited by Eric Blinman, Carl J. Phagan, and Richard H. Wilshusen, pp. 363374. Bureau of Reclamation, Engineering and Research Center, Denver.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

American Antiquity
  • ISSN: 0002-7316
  • EISSN: 2325-5064
  • URL: /core/journals/american-antiquity
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Metrics

Altmetric attention score

Full text views

Total number of HTML views: 1
Total number of PDF views: 137 *
Loading metrics...

Abstract views

Total abstract views: 385 *
Loading metrics...

* Views captured on Cambridge Core between 20th January 2017 - 23rd July 2018. This data will be updated every 24 hours.