What Evolutionary Science Says About Humans and Nature
If modern life often leaves you feeling mentally foggy, constantly stressed, or worn down in ways that are hard to explain, it may not be a lack of resilience or motivation. According to evolutionary science, it may be a mismatch between how humans evolved and how most of us now live.
For the vast majority of human history, our bodies and brains were shaped in natural environments that involved regular movement, exposure to green space, and periods of stress followed by genuine recovery. In contrast, modern industrialised life surrounds us with noise, artificial light, air pollution, prolonged sitting, and continuous low-level stress.
A recent scientific review by evolutionary anthropologists Daniel Longman and Colin Shaw explores how this rapid environmental change may be affecting core aspects of human biology. Hiking and walking in natural environments do not just feel refreshing. They may temporarily restore conditions our biology is still adapted for.
Below are some of the most important and practical insights from this research, and why they matter for hikers and bushwalkers.
1. Our stress response evolved for short threats, not constant pressure
Humans evolved highly effective stress systems designed to deal with immediate danger. When a threat appeared, the body responded quickly, then returned to baseline once the danger passed.
Modern stressors such as traffic noise, workplace pressure, constant notifications, and crowded environments activate the same biological systems. The key difference is that these stressors rarely resolve. The stress response stays switched on.
“Our body reacts as though all these stressors were lions. The key difference is that the lion used to go away.”
Chronic activation of stress systems is associated with impaired immune, cognitive, reproductive, and physical function. Hiking reduces many of the triggers that maintain this stress response at once. Fewer artificial sounds, less visual overload, natural light, and steady movement allow the nervous system to down-regulate.
This helps explain why time on the trail often feels calming in a way that indoor exercise or urban walking does not.
2. Natural environments support attention and mental clarity
Cognitive function plays a central role in daily life, from decision-making to emotional regulation. The research shows that highly industrialised environments place a measurable load on attention, working memory, and executive function.
Experimental studies cited in the review found that people who walked in forested environments performed better on tasks involving attention, memory, creativity, and problem solving than those who walked in busy urban settings.
Urban environments demand constant filtering of noise, movement, signage, and visual clutter. Natural environments tend to engage the brain without overwhelming it.
For hikers, this offers a scientific explanation for the mental clarity many people notice after time on the trail. The brain is not being pushed to process constant artificial input, allowing directed attention to recover.
3. Reduced contact with nature may affect immune regulation
The human immune system did not evolve in sealed indoor environments. It developed alongside regular exposure to soil, plants, animals, and a wide diversity of microorganisms.
The review links highly industrialised environments with higher rates of chronic inflammation, allergies, autoimmune conditions, and susceptibility to infection.
One proposed explanation is reduced exposure to environmental microbes that help regulate immune responses.
Experimental research has also observed changes in immune cell activity following time spent in forest environments, possibly linked to volatile organic compounds released by trees. The authors note that this evidence is promising but based on small sample sizes and should be interpreted cautiously.
Rather than presenting nature as a cure, the research suggests that time spent outdoors may help remove some immune stressors common in urban life, including air pollution, noise, and chronic stress.
4. Humans are physically adapted for endurance movement
For most of human history, daily life involved walking long distances, carrying loads, navigating uneven terrain, and adjusting pace naturally. These conditions shaped human physiology.
The review highlights that physical function remains a key indicator of long-term health and resilience, while modern sedentary lifestyles represent a sharp departure from ancestral movement patterns.
Hiking reflects many of these evolutionary conditions. It involves steady, low-to-moderate intensity movement, varied terrain, balance, and whole-body engagement. This may help explain why hiking feels sustainable and enjoyable for many people, even those who dislike structured exercise.
5. The issue is not modern life, but environmental imbalance
The researchers are clear that industrialisation has delivered enormous benefits, including healthcare, safety, and food security. The problem is not modern comfort itself, but the absence of natural features our biology still relies on.
“We have created tremendous comfort and wealth, but some of these achievements are having detrimental effects on our immune, cognitive, physical and reproductive functions.”
Because biological evolution occurs over many thousands of years, this mismatch will not resolve quickly. Instead, the authors argue that cultural and environmental choices matter. Regular access to natural environments is one practical way individuals can reduce the biological load imposed by modern settings.
Hiking is one of the simplest ways to do this.
A simple question worth considering
If our bodies and brains evolved in natural environments, what happens when we regularly return to them, even briefly?
Hiking does not need to be extreme, remote, or technical to matter. A local trail, a bush reserve, or a quiet forest walk can provide many of the conditions human biology still recognises.
Perhaps the better question is not why hiking feels so good, but why so many of us spend so little time doing it.
Source: Longman, D.P. and Shaw, C.N. (2025), Homo sapiens, industrialisation and the environmental mismatch hypothesis. Biol Rev. https://doi.org/10.1111/brv.70094
A great read!