The Vital Connection Between Nature and Human Health
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Chapter 1: The Importance of Biodiversity
The time we spend surrounded by other living beings is crucial for the health of our microbiome, which in turn impacts both our brain and overall physical health.
Illustration: Kieran Blakey
Historically, until the mid-20th century, the dominant view of life on Earth resembled a fierce competition for survival. Renowned English biologist Thomas Henry Huxley famously described the natural world as a “gladiator’s show,” where only the strongest, fastest, and cleverest thrived.
However, recent insights have reshaped this perspective. In his acclaimed 2020 book, Entangled Life, biologist Merlin Sheldrake uncovers the complex, symbiotic relationships that exist among various life forms. His specialization in fungi reveals how extensive underground fungal networks support and depend on the trees and plants above, which are also interlinked with the insects and animals inhabiting the area.
Sheldrake emphasizes that biologically diverse environments—whether forests, oceans, wetlands, or deserts—are far healthier than those lacking in biodiversity. This principle of "life supporting life" extends to humans and the ecosystems we interact with.
Section 1.1: The Impact of Urban Biodiversity
Research indicates that the variety of bird species in a location correlates with higher life satisfaction. A 2018 study published in Frontiers in Psychology highlighted that city parks rich in ecological diversity—home to various plants, insects, and animals—offered more relaxation and restorative experiences than those with less biological variety.
A more recent study published in Ecological Economics reinforced these findings, establishing a strong link between regional bird species diversity and the well-being of local residents. Joel Methorst, PhD, the study's lead author, noted that the positive effects of biodiversity on well-being are comparable to those associated with financial income.
Moreover, extensive research suggests that spending time in nature, alongside animals and plants, significantly enhances both mental and physical health. Collectively, this body of work implies that our health and happiness are at least partly influenced by our interactions with other living beings. Microbes may play a crucial role in this connection.
Subsection 1.1.1: The Hygiene Hypothesis and Biodiversity
Since 1989, the “hygiene hypothesis,” proposed by American immunologist David Strachan, has gained traction. It originally suggested that early exposure to germs could fortify the immune system and reduce future illness risks. This idea has evolved into what some scholars now refer to as the “biodiversity hypothesis,” which posits that interaction with natural, diverse environments enhances human health by fostering robust microbiomes.
Estimates indicate that each of us carries roughly an equal number of bacterial cells as human cells. Emerging evidence suggests that the types of microbes residing in our bodies—whether in our guts, on our skin, or potentially even in our brains—can significantly affect our overall well-being. A lack of microbial diversity, termed “dysbiosis,” is often found in individuals with diabetes and inflammatory bowel disease, and is also linked to depression and various neurological disorders.
Section 1.2: The Role of Nature in Microbial Diversity
Current research has increasingly focused on factors such as antibiotics and disinfectants that may disrupt our microbiomes. Additionally, dietary choices impact our bacterial populations, creating interest in prebiotics and probiotics. Nonetheless, new findings suggest that the richness of life beyond our bodies is a significant factor in determining the vibrancy of our internal microbial communities.
A recent study published in Environmental International demonstrated that interactions with urban green spaces—such as breathing fresh air, gardening, and touching plants—increased the microbial diversity on participants’ skin and in their nasal passages. The authors concluded that greater exposure to varied outdoor environments could lead to beneficial health outcomes.
This aligns with previous research showing that pet ownership, traditional farming, gardening, and spending time in nature all contribute to positive health effects by increasing our exposure to diverse living organisms and their associated bacteria. Laura Weyrich, PhD, co-author of the study, remarked that their findings help elucidate how time spent outdoors and in nature can benefit human health.
Chapter 2: The Broader Implications of Biodiversity
The first video, "Why nature is good for your mental health," explores the myriad ways that natural environments can enhance our psychological well-being. Engaging with nature can have profound effects on stress reduction and emotional health.
The second video, "Your Brain on Nature: Why Time Outdoors is Good For Our Mental Health," discusses the scientific reasons behind the calming effects of nature and the importance of spending time outdoors for mental health.
In Entangled Life, Sheldrake illustrates the vast community of microorganisms within the human body and emphasizes that distinguishing their “biological identity” from our own is futile. He writes, “Our bodies, like those of other organisms, are dwelling places. Life is nested biomes all the way down.”
There are numerous actionable health tips arising from biodiversity research, many of which have long been recognized for their benefits: spend more time in nature, engage in gardening, adopt pets, and enjoy a diverse diet rich in plants and fermented foods.
While there are various ways to enhance our exposure to flora, fauna, and fungi—thereby enriching our microbiomes—the overarching narrative suggests that the health of our internal microbes is closely tied to the biological richness and health of our environments. If this hypothesis holds true, our individual well-being may be intrinsically linked to the health of our planet. As our Earth suffers, so too might we.