  Production of energy is a foundation of life. Metabolic rate of organisms
(amount of energy produced per unit time) generally increases slower than
organisms' mass. This phenomenon, when considered across different taxa, is
called interspecific allometric scaling. Its origin puzzles scientists for
ninety two years. Here, we introduce a general biomechanical model, and apply
it to modelling dynamic and kinematic properties of motion of mammals,
reptiles, fish and birds. We consider these models from the perspective of food
chain composition, and use them for finding metabolic properties. Food chains
are viewed as entities developing in the process of evolution under the forces
of natural selection, and optimized from the perspective of sharing common
resources of a food chain's habitat among species composing food chains. This
optimized sharing of resources occurs in a way that gives all species
sufficient quantity of resources to reproduce in adequate quantities, thus
preserving the continuity of a food chain, while also serving as a consumed
resource for the rest of a food chain. In this selection and optimization
process, a metabolic allometric exponent represents a quantitative measure of
thus evolutionary found balanced state of sharing of common resources. This
optimized sharing provides an optimal, albeit dynamic, stability of a food
chain in time and space for a given habitat. Certainly, such selection is
framed by physical, physiological, environmental constraints. The comparison of
theoretically calculated values of metabolic allometric exponents with
available experimental data for the maximal and basal metabolic rates showed:
(a) high adequacy of proposed model to real phenomenon; (b) strong indication
that the discovered mechanism of formation of food chains on principles of
natural selection and optimization is a real cause of metabolic allometric
scaling.
