what kind of organism is a city

Cities are complex things and forgetting for a moment about the human social interactions there are so many things and places and interactions with the environment that make it perhaps better represented by a complex multicellular organism.

If you are unfamiliar with this line of thinking, consider Conway's game of Life. Which is a basic simple set of rules on a checker board. The rules are simple, based on any random (or chosen) starting of checkers on the board which squares will remain covered, which will "die". The graphic at left is an example of stepping though these rules and showing how this "thing" moves across the board in a simple motile behavior. Sure, its not living, perhaps its not real ... but then when you look at the biochemistry of just one part of your body (say insulin production) that doesn't look alive either.

Given that Cities can't easily move a static organism is perhaps best which is why I often choose a plant for my comparisons. The interesting thing is though that most plants get their energy needs from the sun while cities rarely get their energy from the sun (although this is changing). So perhaps cities can be compared with the Monotrope family of plants.

These plants are quite unusual in that they rely on relationships with Fungi to survive (and so they're called Myco Heterotrophs). I think this quote from Wikipedia sums up the city well enough too.

Myco-heterotrophs can therefore be seen as ultimately being epiparasites, since they take energy from fungi that in turn get their energy from vascular plants.^{[3] [4]}

This isn't far from a city, as the energy for a city is mostly from the burning of fossil fuels (most electricity is generated from burning fossil fuels) but some solar and some animal power still serves.

multicellular organisms

I think one of the key observations in biology is to discover how complex single cell organisms actually are. Protists in particular are quite complex creatures with distinct observable behavior and complex morphology.

As humans we're clearly multi-cellular organisms, but an interesting view on this is that as humans we are complex members of an even more complex society.

Just as our bodies are composed of organs, which are in turn composed by cells (all of which share a common DNA) our society is composed of organizations and bodies (which essentially consist of rules and definitions) and bound into corporeal form by the law and a common factor of humans (us) to be the 'agents' which carry out the functions of the organization.

If this seems a bit 'far fetched' reflect for a moment on the fact that we regularly describe organisations using vocabulary which comes from nearly the same set as that which we use to describe organisms. Even the nature of the words are similar:

organisation <=> organism

However as the organizations and bodies do not (as yet) think for themselves they rely on us to do their thinking, and so it is valuable if we can think as an organism not as a cell when working within the organisational roles we have.

This viewpoint is one such viewpoint which is facilitated by Urban Metabolism and lends itself nicely to examine (for instance) the operations of a city.

If you're finding it hard to comprehend this try looking at a wonderful new tool like Google Maps, pick a city which you know, and zoom in until you start to see blocks beginning to be separated by streets. It doesn't take much of a leap of imagination to begin seeing streets as vessels of transportation and if you could see the reticulated water and sewage system overlaid on that map then you'd clearly see this as a vascular system.

Viewed this way its easy to see how the organisation of a city can resemble the organisation of a complex multicellular organisation / ism.


Brisbane City at Night
slowing down our time scale shows the cars on the road as like streams though a vascular system (in this case the road). Like all models one of the purposes for representation is to facilitate our understanding of things (not just to have fun), because we (as humans) seem to have a lot of problems understanding what it is that we can't see.

Just look at recent biological history, before we had microscopes and understood that there were micro-organisms we invented all manner of concepts to explain their effects. Without the right way of looking at things we struggle to understand what may from another perspective appear obvious.

Because water (and sustainable use of water) is my personal topic of interest I see great benefits in examining the cities use of water from this perspective.

Multicellular organisms are composed of single cells, which bear great resemblance to eukaryotic organisms. However significantly they can exist in much greater densities than single cell organisms are able to. For example, in our own bodies there are something like more than 50 trillion cells (that's 50 million million folks). This is concentrated in quite a dense area and if it were not for some complex specialisation of roles and development of systems then they would simply not be able to survive in this density.

Now look at human development, as we begun to develop the world around us (to be more suitable) we added structures and created environments to shelter us and look nice.

We wanted gardens and cover from the rain, dry place for bedding (away from pests and parasites) as well us being social creatures we kept living together in communities much like this example.

But just like the problems which a single cell organism faces this all starts to fall apart when population densities grow. Without a system of planning, a method of waterprovision and proper waste disposal we move quickly to areas which look more like this:

Which are no longer nice, no longer separate us from disease and parasites and in fact open us up to problems.

Its easy to forget that Europe was much like this in the period before the Industrial revolution. Its easy to take for granted all the adaptations and changes we have made as a society to enable us to live together in larger and larger groups (could anyone have imagined the population of London being over 7 million people (that's nearly 5 thousand people per square kilometer). Without our sophisticated systems of water provision and waste disposal we would not be able to be living in such a way.

This brings me back to my diagram of a tree (representing plants).

Much like a city a plant is a complex multicellular organism which depends on the environment for its water supply. It gathers water through the roots and channels it through vessels to the sites of metabolic activity, but unlike a city a plant is very particular on how it manages its water. Water out of the system is mainly losses through expiration losses metabolism of water in the Criric Acid cycle.

Both the City and the plant use water and depend on it for the existence, but the tree however is not only more frugal with its water, but has a much greater diversity of mechanisms for reducing water losses and coping with reductions in supply of water.

So, what has this got to do with administration of a city?

Firstly it has to do with choice. A main purpose of science is to study the world in order to be able to make accurate predictions; like "will that bridge collapse if 30 people walk across together". Much of science and our engineering knowledge has come from observations of nature in just this sort of way. By making an analogy (or building a model) with a natural system we can look to see what works in nature and what doesn't.

For example if a plant places all its dependence on water from what it obtains via the roots what happens if one year there isn't enough water in the environment?

Well, some plants will die, some plants will diminish their growth, perhaps only some parts dying.

If such a thing happens to a city (not having enough water) what will reaction of the city metabolism be?

Is it acceptable for parts of the city to die? Remember, that's people we're talking about now, not just cells.

Such a thing can happen and has happened many times in human history. In recent memory the cities have been towns and they could either ship in more water (essentially extending their root system successfully) or they could diminish in size and perhaps even vanish off the map (with the people moving away). If the city is substantially large, and has importance to the broader community then other solutions must be found. These can be expensive.

Such an example can be found in South East Queensland with the 'drought' of 2002/2003 when the city of the Gold Coast came within very close margins to having a failure of the city water supply (IE the dam nearly dried up). The response was to extend pipelines to other dams in the region and undertake an expensive water grid upgrade in order to source more water. As well restrictions were placed on the use of water by the residents.

Essentially in metabolic terms the reaction was control metabolic activity (with economic consequences) and attempt to extend the 'root system'.

The first strategy is not something which is by any vision sustainable, and the second worked in the short term until the water supply started to dry up in more of the region meaning that other 'organisms' could not lend a hand any more.

At this point two strategy's were considered:

1. obtain more water
2. recycle more water

Strategy 1 would be essentially attempting to further extend the root systems, and the approach of generating water by obtaining water from the ocean. While this is a plentiful supply of water it brings with it a problem: salt. The resulting "desalination" plant proposal has to this point in time (some 5 years after its mooting) failed to contribute to the water supply, cost many millions of dollars and will ultimately result in increasing the energy needs of the city by a very large and significant factor. Hey, this has a metabolic equivalent too!

Strategy 2 seems to be attractive, but there are a number of legislational issues which encumber this (in place for good reasons such as human health).

A quick look around the plant kingdom suggests a few other methods for solving the problems after all Mangroves (once so common on the Gold Coast) live in salty water and and Bromeliads still common in the rainforest (and hey, who can forget such a prominent example of a Promelaid, the Big Pineapple, if you've visited the sunshine coast) provide excellent examples of what a plant can with less water as well as how to get more when there is nothing available to the roots.

Summary

Hopefully I've been able to provide an example of how urban metabolism can be used not only as a metaphor for the logical grouping of city needs and wastes for analysis (such as material flow analysis, which is something which perhaps also stems from Wolmans works). Gradually I hope that I have been able to share a little of the concepts and advantages confered by the metabolic viewpoint for systems planning.