The Science of Nature in Human Health
Have you noticed how walking through a forest, gazing at natural landscapes, or even smelling a flower can instantly bring a sense of calm and reduce stress?
This is not just a subjective feeling—it’s an evolutionary mechanism deeply rooted in our biology. Our bodies are made from the same elements and organic matter provided by 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
Fascinatingly, our ancestors on the African savanna found safety in landscapes free of threats and predators. This landscapes activated the parasympatethic nervious system or well know as “rest and digest” a state of the body that when is activated it promotes calmness, energy conservation, and processes like digestion, growth, and repair by slowing heart rate. That same programming remains within us today. Natural elements free of predadors and danger influence our psychological and physiological well-being.
For thousands of years, ancient cultures have recognized the healing properties of the natural world. The Japanese, for example, acknowledged nature’s restorative power and developed practices such as shinrin-yoku (forest bathing). Perhaps this is one reason why much of the research exploring the relationship between nature and health has been carried out in Japan. Indigenous communities have also long understood this power, preserving their appreciation and wisdom through stories and rituals embedded in their collective knowledge.
A Healing Multisensory Experience
When we step into natural spaces, our senses tune and align with the natural world, bringing many benefits.
Smell: Forest aromas or fitochemicals 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, and promote psychological relaxation1.
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 fractal patterns can reduce stress markers by as much as 60%, leaving us with a deep sense of calm and peace2. It seems that in the very geometry of nature lies an ancient language that our nervous system instinctively understands.
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. In this way, the voices of birds act as nature’s subtle reminder that we are safe, allowing body and mind to let go of vigilance and move toward calm.
Microbiome and Direct Exposure
Simple constant contact with healthy soil enriches the biodiversity of our microbiome—on both the skin and in the gut—strengthening our defenses. Moderate sun exposure regulates the circadian rhythm, essential for coordinating organ function, digestion, sleep, and hormonal balance.
The benefits of the natural world on human health are vast, but by no means limited. One of the most significant for our mental well-being is explained by the Attention Restoration Theory, developed by Rachel and Stephen Kaplan. Their research 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.
This article is a condensed version of what I explore more fully in my upcoming book, Nature’s Code. In it, we unravel the science, stories, and adventures that reveal how and why nature profoundly shapes our health and allow us to live longer and healthier.
Author: Ilhui Hernandez
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.
3)Ratcliffe, E., Gatersleben, B., & Sowden, P. T. (2013). Bird sounds and their contributions to perceived attention restoration and stress recovery. Journal of Environmental Psychology, 36, 221-228.