Kleiber's Law
The observation that metabolic rate scales with body mass to the 3/4 power across species spanning twelve orders of magnitude in size, from bacteria to whales.
Used in the Books
This term appears in 4 chapters:
"This flexibility - the ability to use different metabolic engines - often determines survival. Kleiber's Law: Why Size Determines Metabolic Rate In 1932, a Swiss biologist named Max Kleiber discovered something peculiar."
"So why stop at 180 tons? Why not 300? Or 500? The answer is metabolic scaling. As body mass increases, metabolism scales to the 3/4 power (Kleiber's Law). Double the body mass, and you need 2^0.75 = 1.68× the energy, not 2×. This sounds good - efficiency improves with size. But surface area scales to..."
"Mud bathing dissipates heat. Once you're large, the challenge is shedding excess heat, not generating it. This explains Kleiber's Law (metabolic rate ∝ mass^0.75). Metabolic rate scales slower than mass because large animals face lower heat loss per unit mass."
"...plications In biological systems, power law-like patterns appear pervasively. Metabolic rates across species follow power law scaling relationships (Kleiber's Law, explored in Chapter 1). Forest tree size distributions exhibit extreme inequality characteristic of power law-like distributions."
Biological Context
Kleiber's Law means larger animals are more metabolically efficient per unit mass. A mouse uses about 30 times more energy per gram than an elephant. This scaling affects lifespan, heart rate, and many other biological rates. The 3/4 exponent likely reflects the fractal geometry of distribution networks.