Natural Environments and Human Health. Alan W Ewert
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for dangerous or other situations. For example, birds becoming noisy or quiet can signal predators. Rupert Sheldrake (2005) wrote about the many animals that survived the 2004 tsunami in Southeast Asia. He noted that in the 1970s authorities in earthquake-prone areas in China relied on cues from animals in order to evacuate towns. More research is needed in this area; although in a retrospective research project Marapana et al. (2012) found compelling evidence that animals that were not caged or tied were mostly able to escape from the 2004 tsunami. In the Yala National Park in Sri Lanka, no animal deaths were reported, even though it is on the coast.
These previous examples show the evolutionary connections between humans and other elements of the natural world. We need the microbes in our gut to survive and plants need the microbes in the soil to survive precisely because we have evolved together. In some cases co-evolution created mutualistic relationships, connecting humans to natural elements, and prompting the web of life theory that in fact all life is one living system. Other examples, such as human response to music being similar to bird response, show some of the similarities in our evolutionary development with other animals. A final aspect of co-evolution is the mapping of biodiversity and linguistic diversity. Skutnabb-Kangas et al. (2003) mapped approximately 7000 languages and found that high areas of biodiversity predicted high areas of linguistic diversity.
Biological connections
This section provides information about how humans’ biological functions, including physical health, depend on interactions with nature. Many people, if asked whether humans are connected to nature, would say ‘of course’: we breathe the air, drink water, eat plants and animals, and use minerals and trees for shelters. From a purely utilitarian standpoint, the idea that humans are connected to nature is widely recognized. At the same time, a remarkable number of people in Western countries might at first respond to the question with a shrug or a disinterested attitude. While we depend on nature for our survival it is also true that in Western countries people can go for long periods of time without being in natural environments, which can cause us to lose our cognitive sense of our connection with nature and result in a disconnect from nature that can be harmful for both people and nature. If humans believe that they do not need nature they ignore their impact on nature. This physical separation may lead to the false sense that we are no longer connected to nature or even that we can survive without nature by relying on technology and human ingenuity.
However, humans’ physical connection with nature is ever present though it may be experienced differently, depending on economic status and geographic location. For example, during droughts people with adequate financial resources can afford to eat more expensive imported food. People not able to import food on demand because of economic or other reasons may starve. Ban Ki-moon (2012) tells us: ‘Droughts, such as we have recently seen in the United States, Kazakhstan, Russia, Brazil and India, also raise prices in the marketplace—with potential economic, political and security ramifications’. In 2012, 15 million children worldwide starved primarily due to drought conditions and their parent(s) being unable to buy food. In 2011 in Kenya, Ethiopia, Somilia and Djibouti millions of people starved primarily because of drought (BBC News Africa, 2011). In ecosystems called drylands, such as in the Horn of Africa where Somalia is located, the effects of climate change are particularly evident. The intensifying cycles of extreme drought and flooding in this area caused the need for emergency relief for 10 million people in 2011 (Ki-moon, 2012). These numbers illustrate the very real biological connection we have to the natural world and how we are affected by it.
Climate change is altering the geographic distribution of plants and animals. Mosquitoes, biologically connected to humans because they feed on human blood, have increased their range in recent years leading to an increase in human exposure to malaria, yellow fever, and dengue (Reiter, 2001). Cities such as Nairobi and Aursha were purposefully located at an altitude where the climate was unfavorable for mosquitoes, thus decreasing the risk of infection. Due to a warming climate in that area, over 4 million people who once were not at great risk for malaria now are at risk. Additionally, because there are more human-built heated indoor spaces, mosquitoes now have indoor resting sites and can live longer at higher altitudes. The result has been an increase in the mosquito’s ability to transmit malaria in the East African Highlands (Reiter, 2001). In this case, humans are changing the habitat and behaviors of the insects to our health detriment.
Florence Nightingale, Ellen Swallow, and many others raised concerns about the impact of the environment on human health and disease, especially as it relates to clean water and diseases such as cholera. They helped humans modify their behavior and environment, and improved health. Our biological health is absolutely connected to nature. Humans need clean air to breathe, clean water to drink, and nutritious food to eat. Even Hippocrates talked about the significant effect that ‘airs, waters, and places’ have on human health over time (Philo, 2009). Our connection to nature is such that changes humans make to the natural environment can have positive or negative physical effects on health.
Psychological/emotional and spiritual connections
It may be harder to see and feel emotional connections with nature than it is to understand our biological connection, but the examples of evolutionary connections described above also point to psychological, emotional, and spiritual connections to nature. If a plant many miles away exhibits the stress of its caretaker, it implies an emotional or psychological connection. Our psychological connections with nature are mostly demonstrated by: (i) people’s self-report of feeling better when in natural environments; (ii) people performing better on stress indicators or cognitive tasks after spending time in nature; (iii) nature having an immunizing effect on people’s psychological health or people having psychological problems attributed to a lack of nature; and (iv) showing that people’s environmental behavior is related to their emotional attachment to nature or animal and human interactions.
There are many examples of humans simply feeling better after contact with nature. Marghanita Laski (1961) studied spiritual experiences and found that ecstasy usually takes place shortly after making contact with something valuable or beautiful or both. Nature, including bodies of natural water and beautiful natural settings, is the most common trigger that inspires ecstasy experiences. Her research was a combination of literary analysis and survey using a questionnaire. Francis and Cooper-Marcus (1991) asked a sample of university students in the San Francisco area what settings they sought when feeling stressed or depressed. Seventy-five per cent of the students cited outdoor places—wooded urban parks, places offering scenic views of natural landscape and locations at the edge of water such as lakes or the ocean.
John Zelenski and Elizabeth Nisbet (2012) from Trent University in Peterborough, Canada, found in their studies about people’s nature relatedness that people who are more connected with nature report being happier than people who are less connected. They also compared outdoor walking with indoor walking and found that outdoor walks in nearby woods contributed more to personal happiness. Moreover, they found that people tend to systematically underestimate how happy short walks in nature will make them (Nisbet and Zelenski, 2011).
Taylor and Kuo (2009) found that children with attention deficits concentrate better after walking in a park, most likely due to the restorative effect of nature. Berman et al. (2008) found that a relaxing 3-mile walk in an arboretum refreshed people and they showed more of an increased cognitive ability than people who had taken a 3-mile walk in an urban industrial area. In a different study, Berman et al. (2012) found cognitive and affective benefits for people with major depressive disorder, indicating that time in nature could be a clinically viable supplementary treatment for this disorder. Others have found contact with nature to decrease depression and mental illness and increase feelings of self-efficacy, self-worth, self-confidence, and personal contentment (Pretty et al., 2006; Van den Berg et al., 2007).
In her book The Ecology of Imagination in Childhood, Cobb (1977) summarized years of observation and research that showed a correlation between deep experiences in the natural world during childhood and healthy development, adult cognition, and psychological well-being. She found that a strong, loving bond between children and nature is indicative of adult creativity. Chawla (1990) concluded that early experiences in nature lead