Biophilia: Our Bonds with Nature

The pre-frontal cortex refreshes itself in Nature

Edward O. Wilson, the Harvard biologist, wrote a book called The Biophilia Hypothesis which describes “the connections that human beings subconsciously seek with the rest of life”.  He argues that this desire for connection with nature is rooted in our biology. This is not a fantastic leap considering humans share 15 % of their genes (protein families) with rice or 33 % with the honey bee. Or as Arthur Koestler argued, we have an evolutionary history that includes the more instinctive reptilian part of our brain which argues with the enlarged neocortex, the centre for rational thought.

Although this should not be interpreted as irrationalism being a requisite cause for walking in nature. In fact, some researchers have found that it is precisely our rational habits of evaluating the environmental stimuli that allow people in nature to have a pleasant mood and experience. Stimuli in natural environments have shown to modestly attract our attention, unlike dense urban environments with their blaring horns and noisy streets which dramatically announce themselves. This modest focus of attention is like a slight meditation that allows the prefrontal cortex to refresh itself. This thinking is part of Attention Restoration Theory which examines environments that lead to improvements in directed-attention abilities.

Stripmalls...we can do better

These theories may go some distance in explaining the faster recovery of patients in hospitals with a view of nature. In 1984 Roger Ulrich, of the Texas A & M College of Architecture, found that gall bladder removal patients over the course of 10 years with a green view spent 7.96 days in hospital compared with 8.70 days of those with a brick wall view. Ulrich even found that hanging art representing natural landscapes yielded positive effects.

Cubicle nation is not natural

With these kinds of results and natural human tendencies it seems poor design to create sterile work environments which lack signs of nature, yet this is often the case. Nor does it make sense to completely concrete over natural spaces to create boring city blocks and moribund malls. What makes sense is to ‘greenify’ our surroundings as much as possible, while not forgetting that the tree is a ubiquitous component of natural landscapes.

Rainforests: Where Trees Celebrate Life

clouds above rainforest

Clouds form above rainforests from moisture released by leaves

Rainforests, and especially tropical rainforests, is where life thrives with all its originality and creativity. These conditions are wet and for tropical regions, warm. This luxurious climate is perfect for growth, but there is also fierce competition for light and nutrients. It is humid beneath the canopy but pleasantly cool above where water is released through leaves to form clouds. Thus these forests have a dramatic effect on Earth’s moisture and heat circulation while providing 28 % of the planet’s oxygen.

Rainforests have been around for tens of millions of years and have adapted with continental drift and glaciation e.g. the Daintree rainforest in Queensland, Australia, is thought to be 135 million years old and contains about 30 % of all reptile species on the continent. It is thought that not only the excellent growth conditions, but also time, allowed for increased diversity, complexity and symbiotic relationships to form beneath the dark canopy.


Abundant life is beneath the rainforest canopy

This biodiversity in rainforests provides 25 % of all Western pharmaceutical ingredients, yet only 1 % of tree and plant species have been examined. One hectare of rainforest contains approximately 750 tree species and 1500 plant species. A quarter of all insect species are also thought to exist in these forests. We should also be most grateful for tropical forests providing 80 % of our diet…including avocados, coconuts, figs, oranges, lemons, grapefruit, bananas, guavas, pineapples, mangos and tomatoes; vegetables including corn, potatoes, rice, winter squash and yams; spices like black pepper, cayenne, chocolate, cinnamon, cloves, ginger, sugar cane, tumeric, coffee, vanilla and nuts1.


Chocolate comes from cacao plant seeds, native to South American rainforests

Yet we are painfully slow to see their real value. Modern humans have only seen timber, pasture land for cattle and what potentially lies beneath the soil in the form of oil and gas. We destroy most of the real bounty and wealth to create a beefburger. Even indigenous humans who live in rainforests have suffered from this modern greed; 500 years ago there were 10 million Indians living in Amazonia, this has been reduced to less than 200 000 today. Though it is hard to call it greed when most of the value of rainforests is not used for human benefit; ignorance is a better word, yet this also fails to fully encompass repetitive and willful destruction.

The beefburger

Rainforests are often cleared for finally make a beefburger

Decisions are required by all of us. As a human the Earth forms part of our identity and so, even if implicit, the destruction of a vital organ of the Earth is an act affecting all, and requires a response. The trees around us should remind us of this; as their kin are ‘cleansed’ we should reflect on our way of life. For myself, this introversion realises itself in a project to help the Earth, and thereby hopefully ourselves.


Clearing of the rainforests (Greenpeace)


Trees in the City

When humans have concentrated together in places of commerce and culture i.e. cities, the natural landscape has suffered. Woodlands have been cleared and fields have made way for concrete. Most cities, however, retain green spaces and parks though of small relative size. Trees are an essential part of maintaining a natural element in these spaces and they provide far more than aesthetic appeal while at some cost to their stoic selves.

Trees in our midst (Design for London)

Not only is carbon dioxide being absorbed through the leaf stomata of trees, but also carbon monoxide, sulphur dioxide, nitrogen dioxide and ozone.  And not only are these gases harmful to humans but also fine particulates (including cadmium, lead, chromium and nickel) which can be reduced by 60 % in tree-lined streets1. This gift from the trees comes at an expense to their health and leaves can often be discoloured and their growth stunted. Some like the plane tree are more adaptable through the shedding of their bark every year.

Ozone damage on prunus serotina (Swiss Federal Institute for Forest, Snow and Landscape Research)

Shade also has greater consequences than making your lunchtime sandwich more pleasant.  Cars in shaded parking lots (50 % cover) have an 8 % reduction in evaporation of their hydrocarbons. Roads also last longer as their surfaces are kept cooler. In summer, trees reduce the urban heat island effect through shade and the cooling effects of water evaporation from their leaves. In fact the evaporation from one large tree can produce the equivalent cooling of 10 room size air conditioners2.

Un dimanche après-midi à l’Ile de la Grande Jatte (George Seurat, 1884)

Trees attract life, and in higher tree density areas bird populations are also higher, while there is a correlation between expanses of manicured lawns and low bird diversity, suggesting that we could do with less frills and more substance. Psychologically, positive effects on human health have been explained with theories such as the biophilia hypothesis (Edward O. Wilson) and Attention Restoration Theory (Rachel and Stephen Kaplan) – these ideas will be explored in later blogs. Trees offer unconditional service to the whole environment, even in the unsuitable conditions found in cities, and for this we should be most grateful.

  1. Dr Rim Coder, University of Georgia , 1996
  2. USDA Forest Service

The Memory of Trees

Wildfire in California

While humans remember preceding springs and summers with difficulty, trees have these memories as concentric rings across their section. Senility is not an option with weather and climate inescapably etched into their form and being. Each growth season a new ring of wood is added from the cambium, and each ring has a story and a memory. There may have been unmerciful droughts, freezing winters, floods and fires or soft rain and gentle sun. All of these would have left their mark, and all of these would add to the character and appearance of the tree.

Vondelpark in the winter, Amsterdam.

These memories and stories of trees are examined with the sciences of dendrochronology and dendro- climatology, to name but a few. Tough conditions produce narrow growth rings and these can be matched to other data in the area or period. Even a tree crowded on one side by an overbearing neighbour will often result in a narrow section of the growth ring. Tropical trees may have two growth rings per year and some trees growing in glorious conditions may have none, or rather they have one continuous memory.

Growth rings, the memories of trees

Growth rings, the memories of trees (Idaho Forests Commission)

The Sheffield Dendrochronology Laboratory in England has mapped tree rings using a number of different trees to 5000 BC. This data bank allows unknown timber to be matched against the record, much like a fingerprint, and its own story may be revealed. One such story can be read from English oaks, which have many memories and some may live for a thousand years. However, there is one significant ring missing from oaks and other old trees and that is from the year 1816. If you think the last summer was modest, in 1816 there was none. It is thought that dust from several volcanic eruptions influenced global weather patterns to produce a most miserable year. In June of that year snow fell in New York while cold and heavy rains lashed Britain and Indian monsoons were delayed. Frost destroyed crops and trees in China and European harvests were greatly diminished. It was the worst famine of the nineteenth century and riots broke out across Europe and the U.K., putting current austerity protests to shame.

This missing ring shows that trees suffered along with humans, and although absent, its story was very much present, and part of all our stories. Our stories are linked with Nature as much as we try to ignore or forget, and a tree’s memories are deeply woven with our own. They share in part of the collective memory of our planet and as such are part of human identity. We cannot separate ourselves from Nature that easily.