Was there a need for high carbohydrate content in Neanderthal diets?

Abstract

Objectives: In a recent paper, Hardy et al. (2022, Journal of Human Evolution 162: 103105) claim that the physiological Neanderthal requirement for plant carbohydrates may have reached 50%–60% of caloric intake, inferred from modern dietary guidelines and a putative need for high carbohydrate intake in pregnant/breastfeeding women and athletes. The aim of this article is to critically re-examine these arguments under the premise that hominins could adapt to hypercarnivorous diets and low carbohydrate consumption. Materials and Methods: Literature on ketogenic and carnivore diets was retrieved. A case report of a male rugby player voluntarily undertaking a carnivore diet under medical supervision is presented. Results: Human metabolism is highly flexible towards adapting to long-term low carbohydrate intakes by producing and utilizing ketone bodies. The evidence base of dietary guidelines is weak, and carbohydrate intake recommendations for athletes and during pregnancy/lactation are uncertain, making a translation to Neanderthal diets questionable. The studied rugby player maintained his sports performance and health over a 4-months period despite minimal carbohydrate intake. Discussion: Human physiology appears to have an extraordinary ability to utilize ketone bodies as a fuel for the brain and skeletal muscle, in particular also during exercise. The translation of dietary guidelines to Neanderthals and interpretation of studies in subjects not adapted to ketosis may be biased by a “glucocentric” perspective supposing that high carbohydrate intake is necessary for maintaining health. Allowing for the possibility of keto-adaption leads to a more coherent integration of archeological and physiological data.