Life is extraordinarily scalable — the same principles, dynamics, and organization operate across all mammals and can scale over a range of 100 million in size — and this scalability is one of the main reasons life is so resilient and robust.

Even though each organism, cell type, and gene evolved in its own unique niche through Darwinian evolution and natural selection, they have all been constrained to lie on the same scaling line, indicating that something beyond natural selection is at work.

Biological metabolic rate scales sublinearly with mass at a slope of roughly three-quarters (less than one), which means doubling an organism's size requires only about 75 percent more energy rather than double, expressing an extraordinary economy of scale: the bigger you are, the less energy per capita you need.

Given the size of a mammal, one can predict at the 90 percent level everything about its physiology and life history, because any physiological variable or life-history event plotted against size shows extraordinary regularity.

Cities are networks, and the most important network of a city is the population itself — cities are simply the physical manifestation of human interactions and the clustering and grouping of individuals.

City infrastructure scales sublinearly with population: for example, the number of petrol stations per capita decreases as a city grows, and this economy of scale holds to the same degree everywhere in the world (Europe, Japan, China, Colombia), and applies to all infrastructure such as length of roads and electrical lines.

The United States went from less than a few percent urbanized 200 years ago to more than 82 percent today, the planet crossed the 50 percent urbanization mark a few years ago, and China is building 300 new cities over the next 20 years.

Every week until 2050, more than a million people are being added to the world's cities, an ongoing phenomenon that will affect everything.

Cities have a dual nature: while they are the source of major problems, they are also the solution because they act as vacuum cleaners and magnets that attract creative people and generate ideas, innovation, and wealth.

There is an urgent need for a serious scientific theory of cities, meaning a quantifiable framework relying on underlying generic principles that can be made predictive, analogous to how biology can be modeled with universal laws.

It is very hard to kill a city — you could drop an atom bomb on a city and 30 years later it survives, and very few cities fail — whereas all companies eventually die, suggesting cities and companies obey fundamentally different dynamics.

A serious scientific theory of companies should be able to predict when a company such as Google will go bust.

Biology has a mathematical framework based on generic universal principles that can answer quantitative questions about a tree — how many branches or leaves of a given size, the energy flowing through each branch, canopy size, growth, and mortality.

Doubling the size of a city — from 100,000 to 200,000 or from 10 to 20 million — systematically produces a 15 percent per-capita increase in wages, wealth, patents, crime, police, and AIDS cases, together with a 15 percent per-capita savings on infrastructure; this 15 percent rule holds universally regardless of location.

The universal 15 percent scaling behavior arises from social networks — the interactions and clustering of people — which is why it holds identically across cities that evolved completely independently on different continents.

Because cities are governed by superlinear social networks (more per capita as they grow), the theory predicts that the pace of life increases with city size — the bigger the city, the faster life gets — as shown by walking speed increasing with population across European cities, mirroring the reverse pattern of heart rate slowing in biology.

Urbanization has been expanding at an exponential rate over the last 200 years, such that by the second half of this century the planet will be completely dominated by cities.

The tsunami of sustainability problems humanity faces is actually a reflection of the exponential increase in urbanization, because cities are the origins of global warming, pollution, disease, and the concentration of finance, economies, and energy demands.

Organisms grow rapidly and then stop, following a sigmoidal curve; this bounded growth is very good for biology (a reason for its resilience) but very bad for economies, companies, and cities under the current growth paradigm, which instead demands hockey-stick exponential growth.

Across 23,000 US companies, income and assets scale sublinearly with size (number of employees) like biology, indicating companies become dominated not by superlinear innovation and ideas but by economies of scale — namely bureaucracy and administration.