Two articles in a recent issue of American Antiquity explicitly (Gill et al. Reference Gill, Braje, Smith and Erlandson2021) and implicitly (Lyons et al. Reference Lyons, Hoffmann, Miller, Martindale, Ames and Blake2021) perpetuate a common misconception concerning human nutrition. Both articles argue the need for carbohydrates in the human diet. Additionally, both erroneously employ the term “dietary staple” in reference to geophyte consumption.

Gill and colleagues (Reference Gill, Braje, Smith and Erlandson2021) examine archaeobotanical remains from a site (CA-SRI-997/H) on the Northern Channel Island of Santa Rosa, California, to argue an early (11,450 cal BP) use of geophytes (Brodiaea-type corms and Calochortus bulbs) by the inhabitants. Lyons and colleagues (Reference Lyons, Hoffmann, Miller, Martindale, Ames and Blake2021) discuss the discovery of a wapato (Sagittaria latifolia) garden of a site (DhRp-52) near the Fraser River, approximately 20 km from the coast of British Columbia.

According to Gill and colleagues, “rich in carbohydrates, geophytes were important in many coastal areas where protein-rich marine foods are abundant. On California's Channel Islands, scholars have long questioned how maritime peoples sustained themselves for millennia with limited plant resources” (Reference Gill, Braje, Smith and Erlandson2021:625). After a discussion of experimental return rates (measured as kcal/hr), Gill et alia (Reference Gill, Braje, Smith and Erlandson2021:634) argue that marine resources provided abundant energy for the Islanders and that “the caloric value of starchy plant foods may not be the primary factor in foraging decisions.” Consequently, plant-derived carbohydrates played other dietary roles in addition to being an energy substrate. What is the important role in this instance? We are informed, without citation, that carbohydrates are essential for metabolizing meat derived from marine sources (Gill et al. Reference Gill, Braje, Smith and Erlandson2021:634). Surprisingly, carbohydrate return rates are then calculated for Brodiaea-type corms and are shown to be well over the recommended daily requirement (as indicated by the dietary reference intakes of the Institute of Medicine) and the authors state “that the carbohydrate value of geophytes was critical to Islander diets” (Gill et al. Reference Gill, Braje, Smith and Erlandson2021:634). Subsequently, Gill and colleagues (Reference Gill, Braje, Smith and Erlandson2021:634) characterize “geophytes as a rich source of carbohydrates and calories” and, in conclusion, inform us that “such carbohydrate-rich plant foods can be an optimal solution to meeting energy, protein, and essential micronutrient requirements.” Throughout, geophytes are described as a staple food.

Lyons and colleagues (Reference Lyons, Hoffmann, Miller, Martindale, Ames and Blake2021:506) state that “root foods, which supplied vital nutrients and carbohydrates to Northwest Coast communities, were highly sought-after trade commodities and dietary staples.” After calculating production rates, they argue that the geophytes in question made up “a significant contribution to the diet of residents and likely neighboring communities” (Lyons Reference Lyons, Hoffmann, Miller, Martindale, Ames and Blake2021:509). Later, they characterize geophytes as “carbohydrate rich, non-grain resources” (Lyons Reference Lyons, Hoffmann, Miller, Martindale, Ames and Blake2021:515).

Carbohydrates exclusively function in energy (typically measured in calories) production and storage in human metabolism. Carbohydrate is a nonessential macronutrient (Harper Reference Harper, Shils, Olson, Shike and Catharine Ross1999) with adequate amounts of energy being produced via gluconeogenesis and ketogenesis in the absence of dietary carbohydrate (Cahill Reference Cahill1970). There is no carbohydrate deficiency syndrome in humans, and animal studies in which dietary carbohydrates are effectively eliminated do not suffer negative health consequences (e.g., Kennedy et al. Reference Kennedy, Pissios, Otu, Xue, Asakura, Furukawa and Marino2007; Pichon et al. Reference Pichon, Huneau, Fromentin and Tomé2006; Renner and Elcombe Reference Renner and Elcombe1967). Dietary fiber, a carbohydrate, resists human digestion and absorption; therefore, it is not considered a nutrient. Furthermore, the absence of a dietary-fiber deficiency syndrome in humans precludes it from being considered essential in any sense.

As the Arctic ethnologist Vilhjálmur Stefánsson conclusively demonstrated, humans do not need to consume plants, the main source of carbohydrates in most human diets, to survive. Stefánsson subsisted on nothing but animal products for an aggregate of nine years during 11 years of polar explorations (Stefánsson Reference Stefánsson1913, Reference Stefánsson1921) without ill effect (Leib Reference Lieb1926). To allay the skeptical concerns of colleagues, Stefánsson and fellow arctic explorer Karsen Anderson submitted themselves to a supervised experiment in which they ate nothing but animal products for one year, after which there was no evidence that either man suffered any negative health effects (e.g., Lieb Reference Lieb1929; McClellan and Du Bois Reference McClellan and Du Bois1930).

A food is considered a staple if it supplies a majority of a population's annual energy and nutrient needs. Stable isotope analyses for prehistoric populations on the California Channel Islands, which span the past 8,000 years, conclusively demonstrate that marine resources (namely, finfishes and shellfish) consistently provided the majority (>80%) of protein in the diet (e.g., Fauvelle and Somerville Reference Fauvelle and Somerville2021; Goldberg Reference Goldberg1993; Harrison and Katzenberg Reference Harrison and Katzenberg2003; Rick et al. Reference Rick, Culleton, Smith, Johnson and Kennett2011; Schober and Molto Reference Schober and Eldon Molto2011; Walker and DeNiro Reference Walker and DeNiro1986). Likewise, stable isotope analyses for prehistoric coastal populations of British Columbia, including the Fraser River delta, which span the past 6,000 years, indicate that marine resources (namely, salmon and marine mammals) consistently provided nearly all (>95%) of the protein in the diet (e.g., Cannon et al. Reference Cannon, Schwarcz and Knyf1999; Chisholm et al. Reference Chisholm, Erle Nelson and Schwarcz1982, Reference Chisholm, Erle Nelson and Schwarcz1983; Schwarcz et al. Reference Schwarcz, Chisholm and Burchell2014). Therefore, to argue any terrestrial food resource as a dietary staple for either of the peoples in question here is erroneous.

The archaeobotanical evidence clearly indicates the production and collection of geophytes by the populations in question. They had cultural significance, possibly as a trade item; however, in terms of nutrition, their role was insignificant, and geophytes cannot be characterized as a dietary staple. It may seem trivial to call into question the use of a term such as “dietary staple.” However, one of the hallmarks of scientific objectivity is the unambiguous use of terminology, either defined directly or through citation, to avoid purely semantic disputes and allow for the logical analysis of hypotheses.