Urban density – the caution light is flashing

Renowned Australian author, Geraldine Brooks, has made the provocative but valid point that humanity is undertaking the most monumental experiment in the history of evolutionary biology. As a species, we have evolved for an uncrowded life in the openness of natural environments, but we are now flocking to live in very different one – the dense and crowded environment of cities and towns.

This movement is abundantly clear to us in Australia – one of the world’s most urbanised countries – but the United Nations estimates that by 2050, 69% of all humans will be concentrated in urban centres.

This wouldn’t be happening if there weren’t enormous material, social and cultural advantages to urban life. There is no denying that the quality of life we enjoy is attributable in many ways to the urbanisation of our society.

So not surprisingly, there is currently great enthusiasm for expanding our cities outwards and upwards – especially upwards. Indeed, we can be forgiven for thinking that the goal of many politicians, planners and developers is to cram as many apartments or units as possible on every available piece of urban land. Forget about uncrowded openness – higher density is the new desirable, it seems.

But increasing housing and population density comes with hazards.

• As the population of residential buildings increases, trust cooperativeness, friendliness and altruistic behaviour tend to decline. An interesting experimental demonstration of this comes from a study comparing the caring behaviour of university students living in halls or residence (low density), apartments (medium density) or multi-storey towers (high density). The researchers used a subtle technique to measure the students’ neighbourly concern. Stamped addressed envelopes were scattered inside the buildings to create the sense that the “letters” had been lost by fellow residents. The researchers found that, after an interval of four hours, 100% of the letters in the low-density housing had been posted, compared with 87% in the medium density building and 63% in the high-density building.
• Overcrowding is up to 3-4 times more likely in apartments, flats and units than in separate houses. As the number of individuals sharing a given space increases, people have to work harder to co-ordinate their activities with others. Avoiding frustration, conflict and a sense of not being in control is more difficult under these conditions. Overcrowding is often chronically stressful and a trigger for depression, anger, aggression and social withdrawal.
• Overcrowding can be particularly damaging for children. Living in high-density apartments restricts children’s physical activity, independent mobility and active play. An Austrian study  found, for example, that an alarming 93% of children living in centrally located high-rise flats had behavioural problems, much more than children living in houses.
• Even without the added ingredient of overcrowding, urban density is hazardous to mental health. City dwellers have a 21% greater risk for anxiety disorders and 39% greater for mood disorders such as depression. A massive Swedish study of four million people found that the incidence of schizophrenia and depression was, respectively, 73% and 16% higher in the densest urban areas compared with rural regions.

Understanding the link between density and mental health is a work in progress, but a series of German studies puts the spotlight squarely on stress. These studies used healthy volunteers from rural and urban backgrounds (either born or currently living in cities). While their brains were being scanned, the volunteers experienced the stress of being negatively evaluated as they were attempting difficult mental arithmetic tasks.

A consistent and remarkable finding was that “rural brains” and “urban brains” processed the stress via different neural centres and pathways. Unlike the rural brains, the urban brains used a pathway that is dominated by the amygdala, a major source of the dark emotions of anxiety, fear and aversion. In other words, the urban brains performed as if they were primed to respond more negatively to stress.

A possible reason for this is that urban brains have less access to the positive stimulation and buffering effects of nature. As neuropsychologist, Rick Hanson, points out, our brains need plenty of positive buffering because they tend to be shaped more readily by bad experiences rather than pleasant ones. They hold onto negative memories in a “velcro-like” way but are “teflon-like” where positive memories are concerned. This means our brains are disposed to deliver a pessimistic rather than an optimistic view of life.

There is strong evidence that contact with nature can ameliorate this tendency. A study of 350,000 people in the Netherlands, for example, found that the prevalence of depression and anxiety was significantly less for people living in areas with 90% of green space compared with those in areas with only 10%.

For me the message is a no-brainer: approach the densification of our cities with caution. Such densification is inevitable, of course, but let’s do it in ways that prevent damage to individual and community well-being.

• Let’s seek and be guided by objective answers to the questions, when and how does bigger (or denser) in the urban residential landscape come to pose unacceptable risks to health and quality of life?
• Let’s take with radical seriousness the case for greening our buildings, precincts and neighbourhoods (Let’s make all residential design “biophilic design”)
• Let’s do everything we can to ensure that every housing development

– has ample attractive green spaces where people can socialise, garden and play.

– is friendly to children, adolescents, the elderly and shut-ins

• Let’s fight for the preservation, conservation and enhancement of all existing urban green space and bushland

Perhaps this 700 unit, medium density development not far from my home will provide a model to follow by delivering on the promises contained in its billboards.

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