War, Politics, and Faith Shape Urban Wildlife Evolution

The Syrian civil war drove house sparrows to local extinction in bombed neighborhoods. Buddhist prayer animal releases spread invasive bullfrogs across Asian cities.

Racial segregation policies in American cities created genetic bottlenecks in urban wildlife populations. These aren’t sociology stories—they’re evolution in action, driven by the most human of forces: religion, politics, and war.

A sweeping new analysis published in Nature Cities reveals how social and political upheavals reshape the evolutionary trajectories of urban wildlife in ways scientists have barely begun to understand. The international research team argues that ignoring these human-driven forces leaves massive gaps in our understanding of how cities shape life itself.

Sacred Spaces, Evolutionary Consequences

“For a long time we have separated humans from biology. But humans, especially in urban areas, are a very active part of biology, and our decisions have consequences,” explains Elizabeth Carlen, a Living Earth Collaborative postdoctoral fellow at Washington University in St. Louis and co-lead author of the study.

Religious practices create unexpected evolutionary pressures throughout urban landscapes. In Oviedo, Spain, walls built around religious buildings triggered genetic drift in fire salamander populations, creating distinct genetic differences between salamanders inside and outside the walled areas. Meanwhile, in India’s Karni Mata temple, thousands of black rats thrive under religious protection, fed daily by priests and devotees in numbers far exceeding what natural environments could sustain.

These aren’t isolated incidents. Sacred groves in urban India, cemetery habitats in European cities, and temple grounds across Asia all function as evolutionary refuges where different selective pressures apply. Species may experience protection from predation, enhanced food availability, or altered social dynamics—all of which can drive rapid evolutionary change.

Politics Fragments the Urban Genome

Political decisions reshape urban landscapes with profound genetic consequences. The most striking example comes from the United States, where historical policies like redlining and racial covenants created lasting environmental inequalities that affect wildlife evolution today.

Research reveals that these discriminatory practices led to systematic differences in urban green space distribution along racial and economic lines. The downstream effects are measurable at the genetic level:

• Wildlife populations in historically redlined neighborhoods show reduced genetic diversity
• Limited green corridors between minority neighborhoods restrict gene flow
• Parks in poorer areas often feature fewer trees and bushes, reducing habitat connectivity
• These patterns create evolutionary “deserts” where wildlife populations become increasingly isolated

Similar patterns emerge from Europe’s post-1989 political transformation. The collapse of communist governments triggered dense urban development that likely reduced gene flow and fragmented wildlife populations across 15 countries, though researchers note this hypothesis remains largely untested.

War as an Evolutionary Force

Armed conflict creates some of the most extreme evolutionary pressures imaginable. During the siege of Sarajevo, three-quarters of urban trees within the siege line were cut for firewood, devastating habitat corridors and fragmenting wildlife populations. Similar deforestation occurred in Bakhmut, Ukraine, and Kimoka, Democratic Republic of Congo, as residents sought heating fuel during conflicts.

The ongoing war in Ukraine offers a real-time case study in conflict-driven evolution. Russian airstrikes have triggered over 37,000 fires affecting roughly 250,000 acres of Ukrainian forests. Meanwhile, human evacuation from Kharkiv allowed roe deer and wild boar to recolonize urban parks after a decade-long absence, potentially restoring gene flow patterns.

Paradoxically, post-conflict zones sometimes become accidental wildlife sanctuaries. The Korean War’s demilitarized zone, established in 1953, has evolved into an unintended nature reserve where Asiatic black bears, Amur leopards, and yellow-throated martens have returned after decades of absence.

Digital Evolution Tracking

Modern technology offers unprecedented opportunities to document evolution as it happens. “Digital technology has allowed us to revolutionize what kind of data we’re collecting,” Carlen notes. “One of our co-authors published a paper on social media accounts of animal changes during war. So, for example, going through Twitter and Instagram and finding posts that people had put up showing a polecat that’s stuck in the crater of a bomb.”

This approach—mining social media for wildlife observations during conflicts—could transform how scientists study evolution in war zones where traditional research becomes impossible.

The research team emphasizes that understanding these social-political drivers of evolution isn’t just academic curiosity. As urban planners design future cities, considering evolutionary processes could help create environments that benefit both humans and wildlife. The key insight? Cities aren’t just concrete and steel—they’re evolutionary laboratories where human decisions become the forces of natural selection.