by Hannah McConnell
Using spider webs to capture environmental DNA and designing plant-based structures to bring nature’s microbial richness indoors: these were some of the fascinating research projects showcased at UCL’s Bartlett School of Architecture in London, at the Probiotic Cities Symposium that took place in early September. The event brought together experts from urban design, architecture, microbiology, ecology and public health, to explore how exposure to urban and built environments, including microbes and pollutants, contributes to health and disease. Central to the discussion was the question of how cities might be reimagined to support healthier lives for all.
The influence of environmental exposures on health interests me because it closely relates to my PhD research: exploring the relationship between urban biodiversity, such as trees and plants in greenspaces like public parks and private gardens, and human mental health. Growing evidence suggests that the soil and air microbiome may be one pathway through which biodiverse environments influence mental health. The human body is increasingly understood to be a biological system consisting of a host and trillions of microorganisms. Importantly, microbes are not “bad”. Many are fundamental to the functioning of ecosystems and human health. So how do we reshape our cities to reflect this interconnectedness, promote biodiversity on the microscopic scale, and improve human health?
Permanence and impermanence
Adapting our cities presents both enormous opportunities and significant challenges. For some, i.e. owners and developers, solutions might be found in adaptations to the fabric of buildings. We were shown examples of bamboo or fungus-based biomaterials, designed to promote microbial diversity and allow air flow potentially increasing the circulation of microorganisms in indoor environments. For others, i.e. renters who cannot alter or make changes to buildings themselves, a solution might be found in the design of ‘stuff’ that can be kept in the home and moved around.
The quality of ‘permanence’ is desirable in building. Humans want buildings that are built for longevity, with minimal maintenance that will last for a long time at low cost. However, if we want to retrofit buildings with biomaterials to promote microbial diversity, we will need to accept that healthier environments must be less permanent. Even man-made materials are not permanent in the strictest sense, but living walls must be tended to and maintained. It introduces a concept of care for the spaces and structures in which we live as well as the ‘stuff’ in them.
Introducing the concept of care
I was intrigued by this concept of care. In one small study presented, participants were invited to care for a totem-like artefact fashioned from solid wood, with an instruction to mist the artefact once a week over a period of several months with a water spray to promote the growth of ‘beneficial’ microbes. Even though they were told that this process potentially improved the health of indoor environments, some participants found it hard to perceive the artefacts as ‘alive’ and worthy of care, or capable of producing health-promoting benefits. There was no visible change to the object over time – microbes cannot be seen with the naked eye – and benefits that cannot be perceived are hard to appreciate. Does benefit occur even in the absence of care, or does benefit require care to be present? Does perception of ‘aliveness’ matter?
Beyond a human-centric perspective
I am reminded of Robin Wall Kimmerer’s beautiful book, ‘Braiding Sweetgrass’, in which she talks about the concept of reciprocity. Drawing on the teachings and stories of her Potawatomi heritage, she emphasises a moral imperative to care for the land and the spaces we inhabit, because they give us life in return and because we are part of the ecosystem. Practically, we can care for the land by tending to the plants that nourish us, being generous with that which we have, and taking no more than we need. I felt her narrative encouraged a sense of the sacred but worry that this aspect could be overlooked. The imperative to care for something only because of what it affords us, through providing ‘ecosystem services’ including food, water and materials for shelter, is a human-centric perspective. In language, even terms like ‘probiotic’ and ‘beneficial’ are human-centric; indicating that desirable microbiota are those which promote human health, where pathogens contribute to disease. Valuing the world based on what it affords humans fails to capture interconnectedness, to our detriment. I wonder if there is potential in the field of microbiome science to move beyond this reductive view.
Built not just for us
Perhaps the most radical implication of probiotic cities is not the materials they use or the microbes they cultivate, but the different relationship they invite us to have with the living world. Emerging evidence about the role communities of microscopic organisms play in sustaining life requires us to expand our understanding of what is alive. It requires a shift towards animistic thinking – accepting that there is more than what we can see – to viewing surfaces, objects, even the fabric of buildings as potentially being ‘alive’. I wonder what it would be like if we understood physical space to be alive; if we understood ourselves not as separate from the world around us, but as participants in a living world where matter was just as much alive as we were. How might this influence our actions? How would we move through the world? Perhaps it would be with a little more care.