Experts stunned after discovering 'luxury effect' in neighborhoods: 'Humans control everything'

A surprising new finding is reshaping researchers' understanding of city life and exposing structural inequities of urban design.

What's happening?

Scientists studying biodiversity in major cities have found that wealthier neighborhoods host more wildlife, plant life, and a greater variety of indoor insects than lower-income communities, according to the Guardian.

The pattern, documented across species and continents, raises concerns about long-term public health impacts tied to unequal access to nature.

The trend, known as the "luxury effect," first emerged in the late 1990s when ecologists in Phoenix realized that plant and animal diversity had less to do with soil type or rainfall and more to do with household income. Wealthier blocks had greener yards, cooler temperatures, and more species. A $10,000 increase in median household income was linked to a drop in surface temperatures and a rise in lizard diversity.

Since then, scientists have documented the effect worldwide. Black-tailed deer in British Columbia gravitate toward upscale neighborhoods with gardens and golf courses. Studies in North America, China, Burundi, and Australia show richer areas supporting more varied plant and bird life.

Even indoor ecosystems follow the pattern: One survey in North Carolina found that high-income homes hosted twice as many insect and spider species as low-income homes.

Another variable may be less about how those with higher income levels take care of their property and more about average property sizes and distances between homes, along with more wooded spaces in between, compared to lower-income neighborhoods that tend to place houses closer together, with smaller yards. The result leaves less contiguous wooded room for species like deer, lizards, bobcats, and coyotes to flourish.

"It made me look at cities differently," said Arizona State University professor Ann Kinzig, who was surprised the luxury effect holds so well, per the Guardian.

Another biologist put it bluntly: "Humans control everything."

Why is this concerning?

The luxury effect reveals where wildlife is concentrated and exposes health disparities created when access to nature is dictated by ZIP code. Reduced exposure to biodiverse environments has been linked to inflammatory diseases, weakened immune systems, and higher allergy rates. Scientists warn that people living in sparsely vegetated neighborhoods miss out on the microbiome-building benefits of contact with healthy soil, plants, and animals.

From rising asthma cases linked to poor neighborhood air quality to chemical pollution disproportionately affecting lower-income communities, the effect is everywhere. This new research adds another layer: The loss of biodiversity may undermine long-term human health and well-being.

Researchers said the pattern reflects broader social inequities in how cities are built and who benefits from nature.

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What's being done about it?

Cities are experimenting with policies that increase green space in underserved neighborhoods, from urban rewilding programs to green community parks. Some public health experts are advocating for programs that prioritize tree planting, shade structures, and small-scale biodiversity projects in areas that need them most.

Individuals can support efforts to restore urban nature equity by planting native species, backing local green infrastructure initiatives, and advocating for equitable park investments. Successful previous examples include neighborhood tree-canopy campaigns and community gardens that boost health and biodiversity.

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