The Science of Nature in Human Health
Have you noticed how walking through a forest or gazing at a landscape can instantly quiet the mind?
This isn’t mere sentiment It’s biology. We are made from the same elements as the Earth.
We are literally nature itself: from the cells that form our organs to the connective tissues that bind them together.
An Evolutionary Legacy
Our ancestors on the African savanna learned to read the environment for safety.
Open, threat-free landscapes activated the parasympathetic nervous system — the body’s “rest and digest” state — slowing the heart, easing digestion, and promoting repair.
That ancient wiring persists in us today. Cultures across the world recognized this long before science confirmed it.
The Japanese formalized it as shinrin-yoku (forest bathing). Indigenous communities encoded it in ritual and story.
Now, hundreds of studies back what they always knew. That same programming remains within us today.
A Healing Multisensory Experience
Nature engages every sense in ways that restore us at a cellular level:
Smell: Forest aromas or phytochemicals come from volatile organic compounds that enter our respiratory system and are absorbed by the body.
Research shows that walking through forests of conifers, eucalyptus, or cypress increases the levels of compounds such as alpha-pinene and limonene in the blood.
These molecules boost the activity of NK (natural killer) cells, strengthen the immune system, lower adrenaline levels, and promote psychological relaxation 1.
Sight: When we look at nature, our eyes often fall upon fractals—those repeating patterns woven into leaves, tree branches, coastlines, or mountain ridges.
These natural designs are not just visually pleasing; they resonate with our biology. Research shows that fractals gently engage the parasympathetic nervous system which lowers stress levels and promotes relaxation.
In fact, studies by Richard Taylor and colleagues reveal that simply observing mid level fractal patterns can reduce stress markers by as much as 60%, leaving us with a deep sense of calm and peace2.
Hearing: Birdsong carries more than melody—it carries meaning for our nervous system. Across evolution, humans learned to interpret the sound of singing birds as a signal of safety: if birds are chirping, predators are not nearby.
This auditory cue reassures the brain that the environment is secure, letting the body rest. Modern research supports this ancient instinct. Studies show that exposure to natural soundscapes, especially birdsong, can lower stress, reduce anxiety, and enhance restorative processes in the brain 3.
Microbiome and Direct Exposure
Direct contact with biodiverse soil introduces commensal microbial taxa to both cutaneous and gut microbiomes. Some research suggest that this will increas the immune tolerance through mechanisms linked to the hygiene hypothesis and its modern successor, the “old friends” hypothesis. Whereas reduced microbial diversity is independently associated with increased allostatic load and systemic inflammation.
Morning sunlight signals your brain’s internal clock—the suprachiasmatic nucleus—to synchronize your body’s systems. This daily reset coordinates digestion, sleep onset, cortisol release, and metabolic timing. Without it, circadian misalignment quietly disrupts hormonal balance and organ function from the inside out.
The Attention Restoration Theory, developed by Rachel and Stephen Kaplan and reinforced by research at the laboratory of Dr. David Strayer shows how nature helps restore attention, memory, and processing capacity.
In today’s undeniable era of overstimulation—filled with screens, notifications, emails, television, sedentary habits, and endless hours indoors—our cognitive resources become depleted.
Yet when we step outside and immerse ourselves in the natural world, our mental load lightens. Backed by hundreds of experiments, this theory demonstrates that spending time in nature not only restores our attention but also enhances memory and cognitive performance.
Refereces
1) Li, Q., Morimoto, K., Kobayashi, M., Inagaki, H., Katsumata, M., Hirata, Y., … & Miyazaki, Y. (2008). A forest bathing trip increases human natural killer activity and expression of anti-cancer proteins in female subjects. J Biol Regul Homeost Agents, 22(1), 45-55.
2) Taylor, R. P., Spehar, B., Van Donkelaar, P., & Hagerhall, C. M. (2011). Perceptual and physiological responses to Jackson Pollock’s fractals. Frontiers in human neuroscience, 5, 60.
Journal
3) Ratcliffe, E., Gatersleben, B., & Sowden, P. T. (2013). Bird sounds and their contributions to perceived attention restoration and stress recovery. of Environmental Psychology, 36, 221-228.
This article offers a distilled glimpse into the ideas I develop more deeply in my upcoming book, Nature’s Code.
Within its pages, I explore the science, stories, and lived experiences that illuminate how and why nature shapes human health, and how reconnecting with it can extend both lifespan and healthspan.
Author: Ilhui Hernandez