of intestinal microbial life found. Microbes outnumber human cells at least ten to one and perform essential digestive and immune system functions. This relationship between humans and digestive tract microbiota mirrors examples of mutualistic evolution found at the global ecological system levels. These findings have implications for the healthcare and nutrition fields, and highlight the importance of human consumption of certain plants to promote growth of intestinal organisms that help human digestion and promote health.
Similarly, scientists have discovered the essential role of microbiota in plant health, a commensal relationship developed over 400 million years. Microbiota digest nutrients and protect plants from pathogens in a symbiotic relationship with fungi that creates mycorrhizae at plant roots. Discovery of the disruption and misunderstanding of the ecological role microbiota play in human gut and soil systems has caused some people to speculate a relationship between the loss of the organisms and the increase in immune system diseases in humans. Arden Andersen (2004), soil scientist and physician, claims that human health, gut microbiota, and soil health are directly correlated and have evolved concurrently. This evolutionary connection ties human health to the health of the natural environment.
Another connection humans share with nature is similarities in aspects of our response evolution. As one example, Sarah Earp, undergraduate music and neuroscience major, and Donna Maney, a neuroscientist at Emory University, report similar neural responses and pathways activated for birds and humans when listening to music, possibly demonstrating similar evolution of emotional responses to music and bird songs (Earp and Maney, 2012). They found that both music and bird song elicit responses in interconnected regions of human and bird brains thought to regulate emotion. The response of the mesolimbic reward system indicates the same neuroaffective mechanisms (meaning the way our emotions are tapped) in the bird and human listeners; namely, that some music or song results in dopamine release for birds and humans, and certain other music or song results in the activation of the amygdala or fear. This discovery may demonstrate that music shares many similar social functions in humans and in birds such as facilitating social contact, reducing conflict, helping to maintain personal attachments, and communicating emotional states (Koelsch, 2010). This study gives credence to the argument that humans, as well as other species, interact emotionally with their environment, including the natural environment.
Plants, like humans, have been shown to respond to music and emotions. Peter Tompkins and Christopher Bird discuss this phenomenon in The Secret Life of Plants (Tompkins and Bird, 1974) and Cleve Backster, past Interrogation Specialist for the Central Intelligence Agency, has presented his work with polygraph instruments and plants demonstrating emotions or reactions at the Institute of Noetic Sciences and the Institute for Transpersonal Psychology in Palo Alto, California. Backster (2003) reported that plants communicate with humans on an energetic or intuitive plane, demonstrating connection. He measured stress increases in plants in relationship to the stress of their human caretakers thousands of miles away. Backster found the connection to humans’ emotions still strong even if the plants were in lead containers, e.g. as human stress increased plant stress also increased.
Many animals seem to be aware of environmental changes before humans. Aware humans piggyback on the animals’ reactions by using their abilities in sensing and noticing the physical and biological signs 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,
