The paper by Van M. Savage, James F. Gillooly, James H. Brown, Geoffrey B. West, and Eric Charnov explores how body size and temperature influence population growth rates. They propose a theory linking population growth rates (r_max) and carrying capacity (K) to individual metabolic rates and resource supply rates. The theory shows that these rates depend on body size and temperature through metabolic processes, which in turn affect survival, growth, and reproduction. Data from aerobic eukaryotes support the predicted scaling relationships for r_max and K. The study also argues that body mass and temperature, through their effects on metabolic rate, can explain much of the variation in fecundity and mortality rates. Field data for marine fishes support these predictions for instantaneous mortality rates. The theory links individual metabolic and resource use rates to life-history attributes and population dynamics across a wide range of organisms. The paper emphasizes the importance of metabolic rate in determining population growth and carrying capacity, and highlights the allometric scaling of these parameters with body size and temperature. The results show that r_max scales with body size as M^{-1/4} and with temperature as e^{-E/kT}, and that carrying capacity scales with body size as M^{-3/4} and with temperature as e^{E/kT}. The study also supports the idea that mortality rates scale similarly with body size and temperature. The findings suggest that the fundamental metabolic processes underlie the observed patterns in population growth and carrying capacity across different species and environments.The paper by Van M. Savage, James F. Gillooly, James H. Brown, Geoffrey B. West, and Eric Charnov explores how body size and temperature influence population growth rates. They propose a theory linking population growth rates (r_max) and carrying capacity (K) to individual metabolic rates and resource supply rates. The theory shows that these rates depend on body size and temperature through metabolic processes, which in turn affect survival, growth, and reproduction. Data from aerobic eukaryotes support the predicted scaling relationships for r_max and K. The study also argues that body mass and temperature, through their effects on metabolic rate, can explain much of the variation in fecundity and mortality rates. Field data for marine fishes support these predictions for instantaneous mortality rates. The theory links individual metabolic and resource use rates to life-history attributes and population dynamics across a wide range of organisms. The paper emphasizes the importance of metabolic rate in determining population growth and carrying capacity, and highlights the allometric scaling of these parameters with body size and temperature. The results show that r_max scales with body size as M^{-1/4} and with temperature as e^{-E/kT}, and that carrying capacity scales with body size as M^{-3/4} and with temperature as e^{E/kT}. The study also supports the idea that mortality rates scale similarly with body size and temperature. The findings suggest that the fundamental metabolic processes underlie the observed patterns in population growth and carrying capacity across different species and environments.