How ancestral subsistence strategies solve salmon starvation and the “protein problem” of Pacific Rim resources

Abstract

This article provides a theoretical treatment of hunter-gatherer diet and physiology.Through a synthesis of nutritional studies, informed by ethno-archaeological data, we examine the risk of protein-rich diets for human survival, and how societies circumvent "salmon starvation" in the northeastern Pacific Rim. Fundamental nutritional constraints associated with salmon storage and consumption counter long-standing assumptions about the engine of cultural evolution in the region. Excess consumption of lean meat can lead to protein poisoning, termed by early explorers "rabbit starvation." While consumption of fats and carbohydrates is widely portrayed as a pathway to "offsetting" protein thresholds, there are true limits to the amount of protein individuals can consume, and constraints are most extreme for smaller individuals, children, and pregnant/nursing mothers. While this problem is not usually perceived as associated with fish, the risk of protein poisoning limits the amount of low-fat fish that people can eat safely. Compared with smaller, mass-harvested species (e.g., eulachon), dried salmon are exceedingly lean.Under certain circumstances fattier foods (small forage fish, marine mammals, whales, and even bears) or carbohydrate-rich plants may have been preferred not just for taste but to circumvent this "dietary protein ceiling." Simply put, "salmon specialization" cannot evolve without access to complimentary caloric energy through fat-rich or carbohydrate-rich resources. By extension, the evolution of storage-based societies requires this problem be solved prior to or in tandem with-salmon intensification. Without such solutions, increased mortality and reproductive rates would have made salmon reliance unsustainable. This insight is in line with genomic research suggesting protein toxicity avoidance was a powerful evolutionary force, possibly linked to genetic adaptations among First Americans. It is also relevant to evaluating the plausibility of other purportedly "focal" economies and informs understanding of the many solutions varied global societies have engineered to overcome physiological protein limits.

Restorative diets: a methodological exploration comparing historical and contemporary salmon harvest rates

“…In attending to the apparent differences among archeological, ethnographic, and ethnohistorical evidence, Moss (1993) finds that historical ethnographic accounts tend to overrepresent the importance of foods that are harvested by men; that involve complex, dramatic, or high-technology harvesting methods; and that are considered high-status foods-all of which suggest that the importance of salmon might be overrepresented in ethnographic sources (Monks 1987, Gobalet et al 2004, Tushingham et al 2021. We therefore used ethnographic sources to estimate the relative contribution of fished foods, not salmon specifically, to diets.…”

“…To check that the estimate range fits within the biological capacity for people to benefit from, and not be harmed by, salmon, we compared the micronutrient intakes associated with eating salmon at the higher end of the restorative harvest rates of the modelled range to Upper Tolerable Intake Levels for Sodium, Saturated Fats, Vitamin D, Iron, Calcium, Vitamin A (from animal sources), Vitamin C, and Protein as specified by Health Canada (2006). A similar check was employed by Fediuk and Thom (2008), and responds to the criticism from Tushingham, Barton, and Bettinger (2021) that efforts to reconstruct diets for coastal First Nations too often overlook the potential for high intakes of salmon to cause protein toxicity. Any benchmarks that rely on total calories (e.g.…”

“…Sources included academic publications, reports, court proceedings and decisions, and public testimony. Geographically, we considered estimates from within the "Salmon Nation," from Northern California to the North Slope of Alaska (Tushingham et al 2021, Salmon Nation 2022; Appendix 1).…”

New insights into dietary management of polar bears (Ursus maritimus) and brown bears (U. arctos)

“…Humans consuming high protein diets are at greater risk of hyperaminoacidemia, hyperammonemia, hyperinsulinemia nausea, diarrhea, and hospitalization or death due to cirrhosis or liver cancer than those on high carbohydrate diets (Bilsborough & Mann, 2006;Ioannou et al, 2009). At even higher levels of dietary protein content in the absence of fat or carbohydrate-rich foods, the above metabolic aberrations associated with disposing of excess nitrogen produce elevated metabolic rates, severe malnutrition, and, if prolonged, death that was termed "rabbit starvation," "caribou sickness," and "salmon starvation" by early Arctic and Pacific Northwest explorers and adventurers, which is why the carbohydrates of berries, seeds and tubers and the fats of pine nuts, ungulates and marine mammals were so important to native Americans (Tushingham et al, 2020). LaDouceur et al (2014) suggested that captive bear diets should be based on understanding the diets of wild bears.…”