Modeling constraints on the spread of agriculture to Southwest China with thermal niche models Jade D'Alpoim Guedes a, * , Ethan E. Butler b a Department of Anthropology, Washington State University, 310 College Hall, Pullman, WA 99163, USA b Department of Earth and Planetary Science, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA article info Article history: Available online xxx Keywords: Southwest China Rice Spread of agriculture Modeling Millet Climate abstract Understanding how, why and by what mechanisms agricultural practices, technologies and products spread out of their zones of original development is a central theme of archaeology. To date, very few studies have combined agro-ecological modeling with detailed analyses of archaeobotanical remains to outline the kinds of challenges that ancient humans faced as they moved crops into environments different from their original homeland of domestication. This paper employs ecological niche modeling to outline the constraints faced by ancient humans as they moved rice, millets and eventually wheat and barley into the mountainous region of Southwest China. In particular, we propose that moving rice into this region presented considerable challenges for its cultivators and we infer that its spread into this area was facilitated by breeding cold adapted varieties of rice or by combining its cultivation with that of millet. High altitude areas did not take up full-scale agriculture until the introduction of cold adapted western Eurasian domesticates such as wheat and barley. The temperature niche models reinforce the adoption of these regionally varied agricultural strategies and support the significance of domesticates other than rice for the spread of agriculture into Southwest China. © 2014 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction Understanding how the planet moved from one that was populated by hunter-gatherers to one populated by farmers has been a central question in archaeology (Bellwood and Renfrew, 2002; Diamond, 2002; Diamond and Bellwood, 2003; Bellwood, 2005). Examining how agriculture spread out of its original cen- ters of domestication has been the focus of many years of research in both Europe and North America. In these regions a number of models exist for explaining how this spread occurred and why it took the form it did (Zvelebil and Zvelebil, 1988; van Andel and Runnels, 1995; Bogucki, 1996a, b; Zvelebil and Lillie, 2000; Bocquet-Appel, 2002; Rowley-Conwy, 2011). Around the world, certain regions (such as Northern Europe and the British Isles) experienced a long delay in the spread of agriculture and some- times even a return to a hunter-gatherer lifestyle. Many hypotheses have been offered to explain these delays including: climate change (Bonsall et al., 2002; Fuller and Stevens, 2012), challenges presented by the local ecology (Bogucki, 1996b), and the presence of hostile hunter-gatherers (Hodder, 1990). Despite their potential for informing how these processes took place, agro-ecological models examining the constraints on moving domesticates outside their original homelands have, to date, only had limited applications in archaeology. In China, recent research efforts have been put into under- standing how agriculture arose in two different centers of domes- tication: that of rice (Oryza sativa japonica) in the middle and lower Yangzi river valley (Fuller et al., 2007, 2008a; Liu et al., 2007), and that of foxtail millet (Setaria italica) and broomcorn millet (Panicum miliaceum) in Northern China (Bettinger et al., 2007; Lu et al., 2009). However, little effort has been put into examining how an agri- cultural lifestyle spread out of these two potential centers of domestication to become the dominant lifestyle in East Asia. The Sichuan Basin of Southwest China was an important center for the development of complex societies in Bronze Age China (d'Alpoim Guedes, 2011; Sichuan Sheng Wenwu Guanli Xieyuanhui, 1987; Sun, 2013). Indeed, China's first emperor exploited the abundant rice agriculture produced by societies in this area in his unification efforts during the second century BC (Sage, 1992). However, despite the importance this region eventu- ally came to play in agricultural production, recent evidence has * Corresponding author. E-mail addresses: jade.dalpoimguedes@wsu.edu, jadeguedes@gmail.com (J. D'Alpoim Guedes), eebutler@fas.harvard.edu (E.E. Butler). Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint http://dx.doi.org/10.1016/j.quaint.2014.08.003 1040-6182/© 2014 Elsevier Ltd and INQUA. All rights reserved. Quaternary International xxx (2014) 1e13 Please cite this article in press as: D'Alpoim Guedes, J., Butler, E.E., Modeling constraints on the spread of agriculture to Southwest China with thermal niche models, Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.08.003