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Have you noticed how a walk through a forest, or a long look at an open landscape, can quiet the mind almost immediately?

That response is not only sentiment. It has a biological basis. We are made of the same elements as the Earth, and in a very literal sense we are nature, from the cells that form our organs to the connective tissue that holds them together.

An Evolutionary Legacy

One influential idea, the savanna hypothesis, proposes that our ancestors learned to read the landscape for safety. Open, threat-free terrain would have allowed the parasympathetic nervous system, the body’s “rest and digest” state, to take over, slowing the heart and shifting the body toward repair.

That ancient wiring appears to persist. Cultures around the world understood this long before science began to measure it. In Japan it was formalized as shinrin-yoku, or forest bathing, while Indigenous communities encoded it in ritual and story. Today, a growing body of research is catching up with what they already knew.

A Multisensory Experience

Nature reaches us through every sense, and each one offers a different pathway to recovery.

Smell. The scent of a forest comes largely from phytoncides. These are volatile organic compounds, such as alpha-pinene and limonene, that trees release into the air and that we inhale as we walk. In studies led by Qing Li, forest bathing trips were associated with increased natural killer (NK) cell activity, higher levels of anti-cancer proteins and lower urinary adrenaline.¹

Sight. When we look at nature, our eyes keep landing on fractals: patterns that repeat at different scales in leaves, branching trees, coastlines and mountain ridges. Physicist Richard Taylor and colleagues found that fractals of moderate complexity, the kind most common in nature, produce physiological responses associated with relaxation.² Taylor has reported stress reductions of up to 60% in related work. The research is still early, but it suggests our visual system may be tuned to the geometry of the natural world.

Hearing. Birdsong carries more than melody. Over the course of evolution, a chorus of birds likely came to signal safety, since birds tend to fall silent when predators are near. In one study, participants frequently described birdsong as helping them recover from stress and restore their attention.³ The ancient instinct, it seems, is still with us.

Microbiome and Direct Exposure

Direct contact with biodiverse soil introduces commensal microbes to both the skin and gut microbiomes. Some research suggests this exposure may improve immune tolerance, through mechanisms described by the hygiene hypothesis and its modern successor, the “old friends” hypothesis.⁴ Conversely, reduced microbial diversity has been associated with increased allostatic load and systemic inflammation.

Light and the Body Clock

Morning sunlight signals the brain’s master clock, the suprachiasmatic nucleus, to synchronize the body’s systems. This daily reset helps coordinate cortisol release, sleep onset, digestion and metabolic timing. Without regular light cues, circadian rhythms can drift out of alignment. That misalignment is linked to hormonal disruption and poorer metabolic health.

Attention and Restoration

Attention Restoration Theory, developed by Rachel and Stephen Kaplan,⁵ proposes that nature replenishes the focused attention we spend down over the course of a day. Later work supports the idea. A short walk in a park improved working memory compared with a walk through city streets.⁶ Research from David Strayer’s laboratory found that several days immersed in nature, away from devices, was associated with a 50% improvement in creative problem solving.⁷

The need has rarely been greater. Screens, notifications, email and long hours indoors steadily drain our cognitive resources, and stepping outside is one of the simplest ways to let them recover.

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This article is a distilled glimpse of ideas I develop more fully in my upcoming book, Nature’s Code. In it I explore the science and the lived experience of how nature shapes human health, and how reconnecting with it may support both lifespan and healthspan.

References

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. Journal of Biological Regulators and Homeostatic Agents, 22(1), 45–55. pubmed.ncbi.nlm.nih.gov/18394317/
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. doi.org/10.3389/fnhum.2011.00060
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. doi.org/10.1016/j.jenvp.2013.08.004
4. Rook, G. A. W. (2013). Regulation of the immune system by biodiversity from the natural environment: An ecosystem service essential to health. Proceedings of the National Academy of Sciences, 110(46), 18360–18367. doi.org/10.1073/pnas.1313731110
5. Kaplan, R., & Kaplan, S. (1989). The experience of nature: A psychological perspective. Cambridge University Press.
6. Berman, M. G., Jonides, J., & Kaplan, S. (2008). The cognitive benefits of interacting with nature. Psychological Science, 19(12), 1207–1212. doi.org/10.1111/j.1467-9280.2008.02225.x
7. Atchley, R. A., Strayer, D. L., & Atchley, P. (2012). Creativity in the wild: Improving creative reasoning through immersion in natural settings. PLoS ONE, 7(12), e51474. doi.org/10.1371/journal.pone.0051474

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