Why we all need to get out more

Humanity has gone back to its origins. We live in caves again, but the cave is now a glass palace. D

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Nearly a century ago, the only surviving member of the Yahi tribe of North America walked out of the Californian hills and into American legend. Ishi was feted as the last genuine native hunter-gatherer and became the subject of extensive anthropological and biographical research. He was also the focus of some cultural soul-searching. Questioned about civilisation and its discontents, as his biographer Theodora Kroeber reported, Ishi was "sure he knew the cause . . . an excessive amount of indoor time". It was "not a man's nature to be too much indoors", he declared.

Some 90 years after Ishi's death, things are much worse. If you're reading this article, the odds are not only that you are inside, but that you spend much, probably most, of your life indoors - staring at a screen, manipulating words or symbols, attending meetings in brightly lit rooms. You probably spend more and more time on the internet too, shopping, chatting, researching. And exercise? Well, there's the gym in the basement . . .

Homo sapiens passed much of its early history holed up in caves and it is now returning to its origins. For today's postmodern troglodyte, however, labouring in the knowledge economy, the cave is a lofty glass palace. And whereas the souterrain of palaeolithic times remained earthbound, the contemporary version has floated free. It is a multi-glazed, shrink-wrapped work module, sealed off by technology and security systems from anything that interferes with the pursuit of economic gain and career advancement. To enter it, and to ascend by lift to its summit, is to free oneself from trees, wind, rain, sunshine, the earth beneath. It is, almost literally, to abandon nature.

Humans have been trying to escape the exigencies of nature for most of their history - and we are nearly there. The current century will be the first in which most of us live in towns and cities. In 1800, according to the United Nations, only 2 per cent of the world's population was urban. Now the figure is about 48 per cent, and it is expected to rise to 61 per cent by 2030. The UK is already 89 per cent urban.

In the wake of the move into cities has come the great retreat indoors. Indeed, the two migrations have overlapping causes - the decline of outdoor occupations such as agriculture and forestry, the move to a manufacturing and then to a service economy, the search for controlled environments in which economies could be run more predictably. High land prices in cities helped drive buildings into the sky; 20th-century speculative development and building technology did the rest, turning the contemporary office block into a parallel indoor universe, a carpeted and air-conditioned version of the Victorian sweatshop. Meekly, we file in and sit down, grateful for the comforts that appear to surround us. But at what cost to our health and sanity?

According to the government's UK 2000 Time Use Survey, most of our days are now gobbled up by sleeping, working, eating, travelling and screen-watching - activities conducted inside boxes of one sort or another. Less than half an hour in the average day is spent in purposeful outdoor activity. Research in the US suggests that the average American spends 95 per cent of his or her time indoors isolated from nature. The UK's survey is more specific - out of 1,440 minutes each day, it says, we spend precisely one minute in the countryside or at the seaside.

In evolutionary terms, the migration to the "double indoors" of city and building represents a huge and abrupt change of habitat - in the case of Britons, this has been accomplished in the space of perhaps half a dozen generations, as against 350,000 generations or so spent as hunter-gatherers or pastoralists. It would therefore be surprising if there were not some ill-effects. Some we are familiar with. The great urban indoors is an ecosystem occupied by sedentary grazers and in not much more than a generation has made us so fat that obesity and its associated ills - heart disease, cancer, diabetes - now rank among the biggest health problems in the developed (that is, urban) world. As a recent report from the World Health Organisation pointed out, urbanisation is associated with a shift towards "energy-dense" diets, high in saturated fats and sugars. Part of the reason is that our (reasonably healthy) peasant diets are no longer available - so we fall into the hands of the food transnationals. But there may also be an element of compensation: we are eating to cheer ourselves up.

The best-known symptom of our discomfort was the appearance, in the 1980s, of "sick building syndrome". This showed up as a rash of physical and mental ills - from coughs and colds to headaches, tiredness and depression - that beset workers in deep-plan offices, affecting up to 80 per cent of staff. The syndrome remains something of a mystery - are its causes physical or psychological? Faulty air-conditioning is clearly one culprit and ought, technically, to be remediable. Yet, after more than two decades, we have not even solved this problem - one recent study found that staff in air-conditioned offices are twice as likely to be off work and to suffer from ear, nose and throat problems. Could air-conditioning, with its tendency to supply dry, germ-laden, deoxygenated air, simply be incapable of replicating a "healthy" outdoor atmosphere?

New research by the environment organisation WWF has cast light on another potential cause of sick building syndrome - the build-up of toxins, whether sucked in by ventilation or given off by synthetic furnishings and equipment. Chemicals in the blood of volunteers tested by WWF include many found in computers, furniture and fabrics, air-fresheners and beauty products. Buildings - like cities, but far more effectively - have the effect of trapping and concentrating pollution, from whatever source. In that sense alone, it seems, you're better off out of them.

But sick building syndrome also took us into more uncertain territory - the world of lightlessness, for instance. As winter arrives in the northern hemisphere, millions suffer from seasonal affective disorder - Sad, or "winter blues" - caused by lack of sunlight. Spending most of one's life under artificial lights appears to create a variant of this, labelled malillumination syndrome (MIS). The past decade has also thrown up growing concerns about Vitamin D deficiency. Once associated with poverty and long working hours in Victorian slums, it is now resurfacing among affluent troglodytic westerners.

The main source of Vitamin D is sunlight; the best-known sign of its deficiency is rickets. But Vitamin D deficiency, and lack of sunlight, appear to be connected to a host of other conditions. These include, in no particular order, cancer, multiple sclerosis, diabetes, obesity, heart disease, high blood pressure, schizophrenia and infertility. Researchers into Sad and MIS also point to links with mental disorders - depression, fatigue, hyperactivity, aggression. The implications are far-reaching. In one experiment, for example, mice reared under natural light lived more than twice as long as those reared under pink fluorescent lights.

None of this is conclusive but it is, at the very least, strongly suggestive. And what it suggests is maladaptation on a grand scale - a species moving to a habitat that does not suit it. Factor in the competitive pressures that now dominate our synthetic indoor universe - the average lunch break has dropped to 27 minutes, with 20 per cent of workers never taking one, compared to 7 per cent in 1990 - and you have a recipe for chronic stress. So it is no great surprise that people have taken to binge-drinking and overeating (classic reactions to stress) or that depression is so prevalent in the developed world. By 2020, the World Health Organisation says, depression will be second only to heart disease in the global burden of illness.

Forget the science for a moment, however, and examine other, more complex narratives. The first concerns the world we have left behind: the once-great outdoors. In a scientific culture, it is conventional to explain symptoms of maladaptation in physiological terms - in the case of sunlight, for example, the relationships between the retina, the pineal gland, the hormone melatonin and the all-important hypothalamus gland, which regulates sleep and waking cycles, appetite, metabolism, hormone production, reproductive function and mood. Our indoor lives, judging by this logic, deny us fresh air, moisture, oxygen and sunlight, and offer us germs and pollution instead: no wonder they make us ill. But does the story end with physiology? Or, to put it another way, where does physiology end and, say, philosophy begin?

Urbanisation has produced in human beings an often acute sense of disconnection from nature - and in recent years we have seen much research on why this might matter. If people can see trees or greenery, they fall ill less and recuperate better; they are happier, more cheerful and relaxed, more able to concentrate, less aggressive. Apartment blocks with more greenery suffer less crime. Roads lined with trees reduce driver stress and rage. Although it is a bizarre comment on contemporary positivism that we feel we have to prove such effects - every builder of parks and gardens since Nebuchadnezzar took them for granted - the cause remains elusive. Is it an evolutionary adaptation, some encoded memory of the blue skies and green plains of our African origins? We don't know; we can, however, speculate.

Nature is the ultimate Other, the mysterium tremendum et fascinans spoken of by the philosopher Rudolf Otto. It is what prompts poets and peasants alike to metaphysical speculation and ontological wonder. As works such as The Varieties of Religious Experience by William James suggest, it is probably the primary source of the religious impulse, the raw material of spirituality. The Harvard biologist E O Wilson said something like this when he developed his theory of "biophilia" - that human beings have an innate "love" for nature - and he asked: "What will happen to the human psyche when such a defining part of the human evolutionary experience is diminished or erased?"

It is worth reminding ourselves that psyche is the Greek word for soul, and thus that when we banish nature so comprehensively from our lives, the cost may be a good deal more than a dysfunctional hypothalamus. Nor would you have to be a millenarian - or even an heir to the throne - to see, in some aspects of contemporary culture, not least the rise of evangelism, the signs of spiritual malaise. Thoreau wrote: "The indescribable innocence and beneficence of Nature - of sun and wind and rain, of summer and winter - such health, such cheer, they afford forever!" Deprived of much of this - deprived even, thanks to urban lighting, of the traditionally psyche-arousing glories of the night sky - is it any wonder we are all so angst-ridden?

Whether you agree with this or not, a second narrative deserves attention. Confined inside office ziggurats, locked away with fellow professionals, where do we learn the arts of social tolerance - of mixing with others unlike ourselves? Where do we learn new ideas if everyone around us thinks as we do? Environmental determinism teaches that the way we lay out our lives - the patterns and proximities of buildings, spaces, landscapes - vitally shapes their content. Accidental flat-sharers become lifelong friends, heavily trafficked streets destroy neighbourliness. Elites that armour-plate themselves into inaccessibility may thus pose as much of a threat to the health of a culture or a politics as does the spread of gated communities to social harmony. In an indoor world, elites talk only to each other. They learn only what they choose to and encounter "the environment" only rarely.

The world beyond the gates, the forsaken outdoors, thus assumes a wider role. In the case of the "public realm" - spaces nobody owns or controls - it is a source of social learning, of how the "other half" lives. As Sherman McCoy in Tom Wolfe's Bonfire of the Vanities found, this can often be challenging. In the shape of nature, the challenge is more fundamental, because unlike any of its surrogates - TV, films, the internet, PlayStation - the reality is unscripted and unpredictable. It is also unfathomable. In a world without it, one could therefore argue, human beings talk only to themselves, and find the conversation flat, stale and unprofitable. From this perspective, the different narratives fuse, giving us a sharper view of what we are losing; and a sense, too, that Ishi was right. We really do need to get out more.

David Nicholson-Lord is the author of Green Cities: and why we need them (New Economics Foundation, 2003). His novel The Fortieth Night is published this year

This article appears in the 24 January 2005 issue of the New Statesman, 1 in 5 Britons could vote far right