Variable: Nutrients

Nutrients include the full range of food sources used by a human population. The range of tolerance for nutrient gain or loss is relatively small in Homo sapiens (Clapham 1981), making food a critical resource on a continuous basis.

While the absolute caloric and nutritional requirements across our species are relatively stable, this resource varies dramatically by culture (religious proscriptions may make certain food stuffs inedible) as well as climate.

Modern human ecosystems include a wide range of imported foods (for example, espresso coffee beans from Brazil are brewed in Montana gas stations), and few are self-reliant even for short, seasonal periods. The need for food resources certainly influences sustenance institutions such as agriculture. Food carries mythic connotations (the spiritual value of salmon to several indigenous tribes in the United States and Canada; the turkey as a celebratory poultry). Hence, changes in nutrient flows can alter human health, social norms, and cultural beliefs.

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