As mentioned, there was noticeable variation among macronutrient proportions of populations with natural diets, with some noticeably higher in the proportion of protein selected by captive bears. Given that the dietary preferences and optima are expected to be under natural selection, it is thus possible that the intake target of brown bear varies among populations. For example, populations consuming high proportions of protein and very little carbohydrate, such as an in the central Arctic (Gau et al., 2002), may have different intake targets than populations which have evolved under different environmental conditions—even within populations, marked differences in individual foraging behavior (i.e., carnivory versus herbivory) have been observed (Edwards, Derocher, Hobson, Branigan, & Nagy, 2011). Likewise, such dietary adaptation has implications for populations receiving anthropogenic subsidies if their dietary optima shift in response to their nutritional environment, especially if such subsidies no longer become available. At the same time, however, the range of macronutrient proportions observed across populations of this species demonstrates their remarkable tolerance to varying dietary macronutrient proportions.