Urban Apartments Can House More Diverse Fungi Than Huts in the Rainforest, Study Finds

Cleaning chemicals used in urban homes create environments fertile for the rampant growth of fungus, while homes deep in the Amazon have fresher air and contain organisms that are more "natural" for humans, according to a study from Rutgers University.

The study, published Monday in Nature Microbiology, found that the more urbanized a settlement was—meaning the more densely populated—the more diverse the biome of the settlement's homes and its inhabitants were, especially when it came to fungi.

Thus, in their efforts to make their homes more clean or sterile, people living in urban areas may be actually making them more prone to certain kinds of fungi and bacteria.

To conduct the study, researchers examined the microscopic materials in homes as well as the bodies of those homes' inhabitants.

According to the study's abstract, the research covered homes in settlements along an urbanization "gradient." In other words, the study took a look at homes including and between the extremes of the so-called urban-rural divide. The range extended from "a remote Peruvian Amerindian village to the Brazilian city of Manaus," according to the study's abstract. Manaus is the largest urban center in the Amazon basin, with a population of nearly 2 million residents. Other cities, including one consisting of small houses that all lacked indoor plumbing and another medium-sized town with "more modern amenities" were also examined.

Although the urban dwellers reported cleaning their homes more than those living in rural settlements, researchers found that surfaces in the urban homes "had a greater diversity of fungal species associated with human skin," according to the press release. Urbanites were also found to have a greater diversity of foot fungus than their rural counterparts, despite the assumption some may have that the urban homes were "cleaner."

Small group of mushrooms in China
A small group of three closed cup mushrooms features in China on 31 Jan 2016. Jie Zhao/Getty

The research sheds light on some of the disadvantages of urbanization, which is associated with many of the health problems people in more developed countries and areas face today. According to the Rutgers research team, increased urbanization usually goes hand-in-hand with fewer infectious diseases, but is also associated with "obesity, asthma, allergies, autism and other disorders." Further, urban dwellers' microbiomes—the helpful bacteria in our bodies that help digest food and perform other functions—are drastically less diverse than those of rural dwellers.

The study's authors said more research is needed to explore the effects of urbanization on the health of humans, a species originally adapted to live as hunter-gathers in small groups.

"We are just now starting to quantify the effect of cutting ourselves off from the natural environment with which we as humans co-evolved and of replacing it with a synthetic environment," study co-author Rob Knight, a professor at the University of California-San Diego, said. "What's next is to identify the specific differences associated with urbanization that have a health impact and to design interventions to reverse them.