The Rules of Growth: Organisms, Cities and Companies

What do living organisms, cities and businesses have in common? They all have organic characteristics: they’re born, grow, sometimes shrink and usually die. They all require energy to maintain and grow, and they all must deal with the sometimes undesirable byproducts of their existence.1

Do these wide-ranging behaviors follow simple laws that have explanatory and predictive value? Geoffrey West, a physicist and past president of the multidisciplinary Santa Fe Institute, says “yes…and they are laws of scale.” Such rules “quantitatively describe how almost any measurable characteristic of animals, plants, ecosystems, cities, and companies scales with size.”

The biology and physics that underpin these scaling relationships explain why it is unlikely we will ever discover a land mammal much larger than an elephant or much smaller than a mouse, and never the mythical Godzilla of motion picture fame. Weight rises with the cube of length or height, so that, in order to move, hunt, forage or fight, a creature much larger than an elephant would need muscles bigger than the creature. On the small side, a creature much smaller than a mouse could not exist because its heart could not pump blood through its capillaries. It would need a completely different body plan, such as that of an insect.

Likewise, through the lens of scaling, we can understand why, despite life expectancy increasing by leaps and bounds in the modern era, we should not expect to live beyond age 125. People wear out not because they are overworked, but because their cells are. Metabolism, the internal engine or “fire” of life, damages cells at predictable rates and that process puts a limit on how long we can live, even if all diseases become curable or preventable.

We can also find, in the vocabulary of scale, reasons why cities grow to mammoth size – several metropolitan areas now house 40 million people – even though common sense suggests that smaller units might be more efficient and pleasant. Some of these megacities are evolved versions of settlements that were established millennia ago by people seeking the same kinds of business and social connections that people moving to cities in contemporary society pursue now.

Businesses, which are superficially like cities in that they are aggregations of people pursuing some activity in common – reach their scale-driven size limits fairly quickly and have surprisingly short lives, although with a long tail: one Japanese business, a builder of Buddhist temples called Kongō Gumi, “lived” for over 1,400 years.

Scale, argues West, explains all of these phenomena.

West makes a valuable contribution to one of the overarching challenges of our times: how to expand the benefits of economic growth experienced by the developed world to billions living in poverty in the developing world while at the same time dealing with twin environmental challenges of pollution and changes to global temperatures. His contribution is the “scaling toolkit,” which helps us better understand the resource dynamics of human interaction, people, cities, countries and the world.

An author who reaches this broadly is bound to overstep. The usual rule applies: anyone who thinks they have found a single explanation for everything, hasn’t. There are limits to what can be explained by scaling factors.

West calls for a “Manhattan-style project or Apollo-style program” in pursuit of a “grand unified theory of sustainability,” based on his concern that matters of scale could someday threaten the existence of the human race. I suspect he’s talking his book. West’s institute and career would benefit immensely from such an effort. Or it could be just what the world needs. We don’t know. However, for the non-scientist, West’s story of scaling opens a window to the hows and whys of resource dynamics in a growing world economy.