The Environmental Mismatch

Where have humans evolved to live?

In nature meaing humans have evolved to thrive in this environment

Where do humans live today?

In cities. Humans are now described as urban species but are potentially mismatched to this environment

What is an overview of what a city is like?

Cities drive economic growth as well as allowing access to education etc.. However, less physical activity is needed in city. Cities also have stressors: transmission of disease, air and water pollution, noise pollution, artificial light

What happens after spending time in nature?

• Cognitive function improves (problem solving ability, creativity)

• Immune function improves (more anti-inflammatory cytokines than in the city, gives cancer protection)

• Reproduction function improves

• Physical function (can run faster and harder and lift heavier after a visit to the forest)

What were human ancestral environments like?

Human ancestral environments, particularly those of early hominins, were diverse and included open savannas, grasslands, and dry shrublands about 200,000 years ago

What happened to the environments as the climate cooled and dried?

They transitioned from forested areas to more open woodlands and savannas

What happened 100,000 years ago?

Homo sapiens began migrating out of Africa and populated parts of Europe and Asia. Here they adapted to different climates and environments

How much of the human population lives in urban environments?

50-80%

What are cities and towns?

Densely populated settlements with infrastructure designed for living, working, and transportation. They feature high-rise buildings, roads, public transportation, and essential surfaces like hospitals, schools, and markets

What are the benefits of urban environments?

Increased social activity and better access to healthcare services and food mean we have to put less energy into finding resources and have time for other things

What are the negatives of urban environments?

Air, noise, light pollution all cause health issues and have effects on stress. Ease of transport and access to resources means we become more sedentary which can cause obesity. Increased risk of infectious diseases due to compact living

How has evolution and urbanisation occurred?

Rapidly, almost too rapidly for humans to adapt to

How do humans impact the physical environment?

In many ways such as pollution, burning fossil fuels, and deforestation. These changes have triggered problems such as climate change, soil erosion, poor air quality, mass extinction, and undrinkable water among other effects

What is the environmental mismatch?

The lack of fit between an organism's traits and its environment It arises from when a species environment that it is evolved for rapidly changes and the species cannot adapt. For example, humans have evolved to live in nature but instead we are living in urban areas

What does the environmental mismatch involve?

• The transition to modernity rapidly reshaped environments, yet the slower rate of biological evolution limits phenotypic change. This results in evolutionary mismatch

• The phenomenon by which previously adaptive alleles are no longer favoured in a new environment

• Eg. Moths and some species of nocturnal flies navigate in the dark and they evolved to use the moon for direction. But due to the invention of artificial lighting, many moths and flies are drawn to street lamps and indoor lights instead

What is evidence that chronic stress is high today?

• Increased risk of mental health issues if you live in a city - mood and anxiety disorders are more prevalent, for example, you have a 21% increased risk for developing anxiety if you live in a city

• Incidences of schizophrenia double for people born and raised in cities

• This shows urban environments negatively affect mental health and cause high chronic stress

• There are links between the urban environment and first time social stress processing which suggests that brain regions differ in vulnerability to this stress factor

What is evidence that suggest that nature reduces stress?

• Spending time in nature has been shown to reduce salivary cortisol and alpha amylase, two biomarkers for stress levels, indicating reduces stress

• Spending time in nature has been shown to reduce heart rate and blood pressure which both indicate reduced stress

• Natural environments have been shown to aid in the recovery of mental fatigue and cognitive overload

• People living in cities with easy access to parks and green spaces report lower levels of stress compared to those with limited access to nature

• In an 8 week study of 36 urban dwellers, they spent 10 minutes or more a day, 3 days a week, in nature. Their salivary cortisol in a NE produced a 21.3%/hour drop and for salivary alpha amylase, there was a 28.1%/h drop

How does nature benefit human biology generally?

Globally, more than 20% of mortalities can be avoided through healthier environments (clean air, water, food, improved mood)

How does nature benefit immunity?

• Sets of studies point towards immunological improvements from exposure to nature, by boosting immunoregulatory pathways

• The impacts of environmental stressors have led to a significant rise of diseases, such as non-communicable diseases which are today the most frequent causes of death worldwide

• The majority of studies observed anti-inflammatory effects of being in nature, and all other immunological measures provide a positive relation with nature (nature = improved immunity)

• Relief in chronic inflammatory diseases such as asthma from exposure to the natural environments give a solid evidence base for anti-inflammatory, anti-asthma, anti-allergic effects upon inhalation of natural substances such as BVOC (biogenic volatile organic compounds)

How does nature benefit humans psychologically?

• The benefits of nature will increase psychological well-being, positive effect on happiness, social cohesion and engagement giving people a sense of purpose in life, improving manageability of life tasks

• Improves cognitive functions like memory and retention

• Reduces cognitive inhibitions like ADHD

• Maintains the circadian rhythm which has a broad control of our biological functions and well-being

• Raw materials in natural environments can improve cognitive processes such as creativity