Building resilient cities: human evolution and climate adaptation solutions

Around 250BC, Mesoamerica was in the grip of significant climate change. Rainfall patterns shifted without warning, bringing about severe droughts that threatened Mayan society. 

Yet the population quickly devised an effective response. It embraced adaptation, developing advanced agricultural, water and forest management techniques, including raised-field farming and sophisticated irrigation systems. To a growing number of scientists, the Mayans' success sheds light on how we might address our own environmental probelms. 

According to Professor Colin Shaw, an evolutionary anthropologist at the University of Zurich, the climate change unfolding today presents humanity with its most urgent adaptation test yet: that of redesigning society so we can withstand temperature rises beyond 1.5°C and more frequent heatwaves, floods and droughts. 

And it is his view that our evolutionary history can offer valuable insights to help us build more resilient and adaptive environments.

“For humans, there’s a multi-faceted way of adapting,” he explains. "You should probably think about how cities can adapt in this way too."

Prof Shaw was speaking on the sidelines of The Klosters Forum, an annual conference that brings architects, engineers, academics and investors together to debate the challenges society faces in adapting to severe weather. During the three-day gathering, participants discussed how adaptation and resilience technologies are not only transforming urban environments but offering strong investment opportunities.

At the most basic level (light grey box in Fig. 1), humans deal with environmental stress by way of behavioural and physiological responses. When it gets cold, we seek shelter or wear warm clothing. Our bodies also respond by sweating to cool down in summer.

At the next level of adaptation hierarchy (dark grey box), people can exhibit what Shaw calls “phenotypic plasticity”. These are longer-term changes in our physiology or behaviour. This can include, for example, increasing our physical fitness through regular exercrise.

Epigenetic inheritance, meanwhile, refers to human adaption that takes place across generations. When our parents overcame challenges they faced growing up — such as malnutrition or obesity — this resilence can have positive effects on our own biology, increasing our resilience.

The last layer of human adaptation comes in the form of natural selection, or the favouring of genes that enhance survival under new environmental conditions.

For centuries, this layered adaptive capability has preserved internal societal stability, or homeostasis, even as external pressures fluctuated. For example, people living at high altitudes, such as the Himalayan Sherpas, have developed unique genetic traits that allow their bodies to use oxygen more efficiently, thereby conserving muscle energy levels in the mountains and significantly enhancing their performance in climbing.https://www.pnas.org/doi/10.1073/pnas.1700527114

For all this apparent success, Prof Shaw urges caution. The rapid industrialisation that has occurred over the past several decades has created profound "environmental mismatches”, where the modern world diverges sharply from the physcial environments our bodies primarily adapted to. New stressors— excess heat, microplastics or noise and air pollution — can undermine health and resilience and, ultimately, evolutionary fitness – or the ability to survive and reproduce, he says. 

Even so, cultural innovations, such as new building design, have played an outsized role in humans' ability to dampen the detrimental effects of environmental change. Here, blending technological innovation with evolutionary insights may offer a promising path forward.

"The environmental mismatch decreases resilience,” Shaw says. "For example, chronic stress shuts you down. For the built environment, we should design systems that enhance human biological functions — (for example) immune, cognitive and physical — and reduce chronic stress.”

A few practical applications emerge from this approach. For example, incorporating microclimate designs — including nature-based solutions such as tree canopies and green roofs can reduce urban heat stress. Water treatment and recycling facilities or energy-efficient heating, ventilation and air conditioning (HVAC) technologies can also help.

The key is to stack up multiple solutions to build layered defences against adverse climate impacts.

“If you are more complex, you’re more resilient. You have more tools to defend and rebuild yourself,” Shaw says.

Using our evolutionary past as a guide, our cities and infrastructures can be built with flexibility and diversity robust enough to cope with a changing planet.