Archaeological investigations of hunter-gatherer site structure have remained largely descriptive, despite significant explanatory advancements by evolutionary approaches to foraging behavior and ecology. To date, calls to incorporate site structure studies within this behavioral ecological framework have largely been ignored. We suggest there is a clear explanation for this. At large spatial extents, human behavior is constrained by patterned ecological variability, as such, a general theory of behavior is likely to characterize key aspects of human decisions. At small spatial extents, human behavior is not constrained by patterned ecological variability, therefore, the human decisions that produce site structure should be driven by mechanical constraints or random variation. However, variation in site structure may be ecologically relevant inasmuch as it informs on landscape level variation in humanenvironment interactions. Drawing on ethnoarchaeological data collected in collaboration with Martu, Aboriginal foragers in Western Australia, here we test empirically-derived, mechanistic predictions on site size and material size sorting to show how these can inform theoretically-derived, adaptive predictions from the Marginal Value Theorem. Results show that site size increases with the number of occupants and hence, the amount of in-patch foraging competition, while size sorting increases with the duration of occupation and hence, in-patch residence time. Combined, these attributes of site structure can be used as proxies of foraging behavior to explain variability in overall foraging yields. With this approach, site structure can provide insights into foraging decisions that can be examined through a general theory of behavior.Ecological and evolutionary approaches 2 in hunter-gatherer archaeology continue to 3 make tremendous strides toward explain-4 ing variation in subsistence (e.g., Broughton 5 et al., 2011; Speth, 2010), settlement (e.g., 6 Byrd et al., 2015; Winterhalder et al., 2010), 7 technology (e.g., Surovell, 2012; Stevens and 8 McElreath, 2015), storage (e.g., Morgan, 9 2012; Whelan et al., 2013), and demogra-10 phy (e.g., Kelly et al., 2013; Williams et al., 11 2015). But despite this progress, studies of 12 site structure remain largely descriptive (e.g., 13 Hill et al., 2011; Speth et al., 2012).14 O'Connell (1995) made this same obser-15 vation twenty years ago, noting the dispar-16 ity between ethnoarchaeological studies of 17 faunal remains and those of site structure. 18 While the former were advancing successful 19 explanatory frameworks, the latter remained 20 stagnant. O'Connell suggested a simple, yet 21 under-appreciated reason for this difference: 22 studies of faunal remains were building on the 23 foundations of a general theory which pro-24 vided predictions a priori about how individ-25 uals are expected to behave in particular cir-26 cumstances, but studies of site structure were 27 based only on observations a posteriori with-28 out any guiding theory. Because the former 29 predic...