Scalability in Living Systems

[L]iving systems such as individual organisms show a shocking consistency of scalability. Animals, for example, range in size over ten orders of magnitude from a shrew to a blue whale. If you plot their metabolic rate against their mass on a log-log graph, you get an absolutely straight line. From mouse to human to elephant, each increase in size requires a proportional increase in energy to maintain it.

But the proportion is not linear. Quadrupling in size does not require a quadrupling in energy use. Only a tripling in energy use is needed. It’s sublinear; the ratio is 3/4 instead of 4/4. Humans enjoy an economy of scale over mice, as elephants do over us.