Energy and nutrient modelling of human evolution

Abstract

ENERGY AND NUTRIENT MODELLING OF HUMAN EVOLUTION Background. During evolution, human encephalisation resulted in high energy use by the large brain in proportion to the body. Adaptations to increase energy intake or reduce total body energy to redress this imbalance may have involved 1) highly developed neural appetite pathways including the dopaminergic mesocorticolimbic self -reward system to enhance energy dense food intake 2) an expensive tissue trade off including a short adaptable gut that relies on a higher energy omnivorous diet 3) slow growth and development and thus careful preservation of cellular integrity to reduce oxidative stress and allow longevity 4) inhibition/alteration of energy expensive vitamin and co-factor synthesis and a dependence on the wide variety of food micronutrients. It appears that many such food micronutrients are modulating cellular energy use, and that micronutrient quality must be built into energy requirements. Concurrently, humans were developing technologies such as tool use and fire to further expand food quality and quantity. However, the neural self reward aspect systems pushed technology to favour high and secure energy yields. Animal husbandry and plant crop farming lead to selective breeding for high fat, starch and sugar produce, at the expense of micronutrient variety and volume. Once technology progressed to factory farming, and mechanised and chemical food processing systems, proportions of food micronutrients/macronutrients were markedly altered. Humans are driven to consume addictive energy dense foodstuffs but (unconsciously) neglect to acquire adequate micronutrient volumes. They are forced to attempt to store the energy firstly safely in subcutaneous adipose, then centrally around viscera, and finally in non-adipose cells where glycolipotoxicity occurs. Aims: We plan to start developing new dynamic energy equations, with reference to Dynamic Energy Budget (DEB) models for other biological systems. Ultimately, the ‘ideal’ prehistoric fit and healthy, lean hunter-gatherer will be compared with the contemporary sedentary and (metabolically) degenerate, obese ‘westernised-diet’ consuming human. Method: Principles of DEB and mathematical modelling of energy use will be reviewed with respect to human metabolism and different diets.