Cities report higher incidences of depression and mental health disorders. Lack of greenery in modern cities could be a major cause.
Anthropologists say that humans, as a species, first originated in the grasslands of Africa. Not in the deserts, not on barren rocky terrains, neither in the dense rainforest, nor in the swamp and obviously not in the ice-covered mountains and polar regions on the planet.
Our ancestors were indeed forest dwellers. But, as we gradually transformed into something more closer in appearance to modern humans we were already out of the jungle onto the grasslands, digging roots and hunting wild animals for breakfast, lunch and dinner.
For thousands of years our environment didn’t change much. It changed once we began to migrate out of grasslands along the coastline in through deserts crossing mountain ranges, valleys and rivers. Our evolutionary history accustomed our nervous system to a variety of environments and colours. We saw lush greens, ripe yellows, lucrative reds and cool blues, which we learnt to associate with pristine habitats. We also saw rugged browns, rusty reds, sandy yellows, lifeless greys, scary blues and glaring whites which we associated with unsustainable habitats for our species. Out of all of these shades, green was the colour we settled to rely on the most. Green or chlorophyll promised the presence of food and water and life, which meant a chance towards survival. That is just how our nervous system became attuned to the different colours found in nature.
From hunter-gatherers we transformed into agriculturists. Instead of being entirely dependent on nature for our survival we manipulated our surroundings to suit our needs. By bringing vast stretches of land under cultivation we changed the structure of our habitats. Agriculture formed the basis on which civilizations were built. The advancement of human civilization brought drastic transformations in our lifestyle and surroundings. More cities were built, more lands were cultivated to feed the growing human population.
Today, more than half of the human population live in cities. A much more comprehensive report, however, places the estimate at 81%. There is an aggressive urbanization drive across the world for sustaining an ever-increasing human population. However, with each step towards urbanization we are becoming more detached from greenery which had been our natural habitat for a massive chunk of our evolutionary history. This detachment is affecting our physical and mental well-being.
Depression – a common illness among city dwellers
Cities offer people with higher income, improved standards of living, better education and also a vibrant lifestyle. But, all of these advantages come with a cost. There is the burden of pollution, lack of social cohesion, higher competition, stress, artificial surroundings and many more. Many city dwellers complain of a feeling of emptiness stemming from lack of satisfaction with their urban lifestyles.
Nature therapy has proven to provide relief from a multitude of mental illnesses in many cases among urban residents. Which leads to the assumption that lack of nature may be a leading cause behind higher incidences of depression among urban people. Many psychological disorders owe their origin to the excessively artificial surroundings of modern humans living in urban areas detached from nature.
Now, why is that?
Some studies have shown that humans have a preference towards savanna-like landscapes or simply grassland intermixed with trees and shrubs. We owe this to our origins in a savanna-like landscape back in the plains of Africa and have thus learnt to associate certain cues common in such a habitat with our ultimate survival and well-being. This theory is termed the savanna hypothesis.
But it is not just savanna-like landscapes that elicit such satiating experiences. Temperate forests also help reduce stress promoting physical and mental well-being. Shinrin-yoku or forest bathing is common in Japan and has proven helpful for many people experiencing mental health problems due to stress.
Even man-made green agricultural landscapes, gardens, indoor plants and virtual viewing of natural landscapes have shown positive psychological responses in people suffering from mental illnesses and stress-related disorders.
Taking all the above observations into account it appears that it is nature scenes and greenery rather than the type of landscape that helps with alleviation from psychological stress responses stemming from continuous residence in artificial urban environments.
Depression is our adaptive response to survive stressful environments
Mental depression is often seen as a negative outcome. However, mental depression is not all bad. There are certain positive sides to depression which serves our adaptive purposes, ultimately benefiting us in our long-term survival goals.
Most of us recognize depression as a mental state that has a dampening effect on the spirit. When depressed, both the body and the mind seems to suffer from a lack of incentive to perform their normal activities. Depression manifests itself as lowering of physical activity, cognitive decline and lack of motivation which can be summed up to a ‘sad mood’.
But, what if we view depression as the body’s own mechanism to avoid stressful situations?
Winter depression or the Seasonal Affective Disorder (SAD) can be a mechanism to induce the body to step away from wasteful activities during a period when resources are in short supply. Winter is identified with falling leaves, browning foliage, reduced daylight, increasing cold, snowfall and gloomy skies – all of which provoke depressive feelings to some extent. It acts as an indication as if to say – ‘Nature is going into a state of recuperation and so must we.’
Similarly scarcity of natural elements in the immediate surroundings of a person can lead to stress, sad moods and declining cognitive function. Lack of nature equates to difficulty in acquiring the basic necessities of life like food, water, clean air and shelter – dire living conditions in other words.
The modern human mind interprets cues in its surroundings in a manner that aligns with ancient survival instincts passed down through generations, field-tested to ensure survival.
In this light, depression, could be something similar in principle to torpor or hibernation, ensuring maintenance through tough circumstances.
Greenery hypothesis: The positive effects of green
Cities today absolutely lack in greenery. Depression among urban people could be the manifestation of an adaptive response to the absence of cues that signal suitable habitat.
Greenery signifies ample rain and availability of water, presence of various life forms and thus food, resources to build shelter and cultivate the land. Droughts on the other hand paints an opposite picture and were causes of great suffering for our ancestors. Excessive lack of greenery in urban areas simulates a picture akin to drought like conditions.
The greenery hypothesis states that absence of greenery in urban areas can lead to stress and cognitive decline in urban residents due to a negative adaptive response, as discussed above. Restoration of surrounding greenery provides relief from stress and depression in such individuals.
The magnitude of this effect may not be similar in rural residents who are accustomed to the presence of greenery in their immediate surroundings. The negative adaptive response could be totally lost among people habituated to life in environments naturally lacking green like snow-covered valleys, deserts and rugged terrains.
The greenery hypothesis also predicts that proportion of greenery is not the only factor promoting mental well-being but the openness of the view is also a determining factor. It probably stems from our natural instinct to apprehend the presence of predators lurking in dense vegetation or behind obstacles that blocks the view.
With greenery being gradually obliterated from the modern cityscape, psychological disorders are predicted to increase. Restoring green and blue spaces in urban landscapes could be a way out of this problem. Protecting and rejuvenating the natural environment in city areas can promote physical and mental well-being among its residents.