Cities, and the infrastructure networks that bind them, are alive.
Life (cf. biota) is a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not, either because such functions have ceased (death), or else because they lack such functions and are classified as inanimate. Biology is the science concerned with the study of life.
Any contiguous living system is called an organism. Organisms undergo metabolism, maintain homeostasis, possess a capacity to grow, respond to stimuli, reproduce and, through natural selection, adapt to their environment in successive generations. More complex living organisms can communicate through various means.
The city has often been likened to an organism, with downtown representing the control functions of the brain. Scientists have examined the city’s metabolism, and ask what nature teaches about cities.
The better analogy is probably that of the superorganism. Like an ant colony, a city (which obviously contain lots of individual organisms, us) and its infrastructure persists over time, taking in and sending out resources. The city grows (or dies) and occasionally sends off spores to form a new metropole.
Money in the urban economy is then analogous to the energy and food supplies needed by more conventional life forms. The more trade, the larger the city can grow. And like a tree which grows up and out, with a rotted out core, the same often happens to cities. Interaction with the outside world, the source of energy or economic resources, takes place at the boundaries of an organism. The super-organism may eventually decide it doesn’t need the inside or finds that is best used for storage. Or it may rediscover its abandoned areas. The tension between agglomeration and external trade is resolved in different ways in different places.
We also talk about the lifecycle of technologies, from birth, to growth, to maturity, to decline, analogizing technologies to living organisms. Individual deployments of those technologies may follow similar lifecycles.
The “production function” of living systems combines fixed and variable costs. As a homeowner we may plant a tree. But if we don’t take care of the tree, its likelihood of long-term success is low. We maintain it. We prune it. We water it. We protect from bugs, and so on. We don’t “set it and forget it” about trees, nor should we about infrastructure. We need to think about the lifecycle of buildings and infrastructures. Eventually they fail or we realize they are going to fail, or we might want to replace them because they are functionally obsolete. To keep them alive we need to monitor, maintain, repair, and eventually rebuild these systems, alternatively we might just abandon them.
Epidemiology studies the state of human health, as measured by the presence or absence of disease, as well as the causes of those diseases, whether genetic, behavioral, or environment. Someone should similarly be responsible for studying and treating the state of urban health, focusing upon the city’s circulatory system, and looking at causes including human behavior and the urban environment (which is usually taken as fixed) in which humans interact. As knowledge from epidemiology leads to treatments by doctors prescribing medicine, nutritionists telling the patient to change his habits, or regulators changing environmental standards, knowledge from transportation leads to treatments by traffic engineers prescribing angioplasty for the hardened arterials of our city, planners building bypasses, or gurus telling us to change our behavior or urban environment.
There is at least one useful lesson from medicine: First do no harm. We would not want a doctor to chop off our arm, and leave a gaping hole for a few decades while he figured out what to do next. We should consider why we permit destruction of functional if not optimal parts of cities well before we have any plan or resources to close the gaping wound with something else functional. The equivalent of a city’s doctors need to require replacement by something other than a vacant lot or surface parking before they permit demolition.
The point is that instead of viewing cities as inorganic discrete objects, we should think about the city as a holistic super organism: where changes to one component have effects on many others, and where decisions now shape the choices available later.