The ecological and evolutionary consequences of systemic racism in urban environments

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Science  18 Sep 2020:
Vol. 369, Issue 6510, eaay4497
DOI: 10.1126/science.aay4497

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Imprints of racism

Cities create challenging environments for many nonhuman species, and the presence of nonhumans in cities influences the health and well-being of the humans with which they share the environment. Distinct urban conditions are created by landscape modification, but the history of this transformation is not equal across urban environments. Schell et al. review how systematic racist practices such as residential segregation, enacted in part through redlining, have led to an unequal distribution of “nature” within cities. These inequities continue to play out in both the ecological processes of cities and the welfare of their residents.

Science, this issue p. eaay4497

Structured Abstract


Human activity and decisions drive all life in cities. Worldwide, cities are characterized by extensive anthropogenic transformation of the landscape, modification of biogeochemical processes, and alteration of biological communities. Underlying all of these characteristics of urban ecosystems is an extraordinary variability in human agency, culture, power, and identity. Though our understanding of cities as ecological systems with distinctive community assemblages and landscape features has broadened considerably, researchers still rarely consider the full range of social drivers that affect landscape heterogeneity. One of the most characteristic attributes of cities is social inequality—specifically the uneven distribution of resources and wealth primarily underpinned by structural racism and classism. Because structural inequalities form the foundation of city infrastructure, urban development, governance, management, and landscape heterogeneity, inequality among humans defines the ecological setting and evolutionary trajectories for all urban organisms. More broadly, systematic inequities have profound impacts on global biological change and biodiversity loss. Many emergent social inequity patterns are principally driven by systemic racism and white supremacy. Hence, centering racial and economic justice in urban biological research and conservation is imperative. Here, we show how social inequalities shape ecological and evolutionary processes in U.S. cities and highlight the need for research that integrates justice perspectives with ecological and evolutionary dynamics.


Although a rich literature demonstrates how historical and contemporary inequities emerge and persist in human systems, a transdisciplinary perspective that integrates social and cultural processes into an urban eco-evolutionary framework remains unexplored. In today’s world, humans often shape the ecological conditions that drive patterns of species distribution and evolution. Distinctive urban landscape features—including reduced habitat patch size, novel plant communities, and increased distance among similar patches—affect key ecological processes such as population dynamics, species interactions, and food web structure. Recent research emphasizes that socioeconomic and demographic factors predict within-city variation in diverse environmental conditions. Humans directly control urban plant, animal, and microbe communities. Further, decisions about urban resource management are often dictated by a subset of individuals and institutions with social or economic capital. These decisions can bias the distribution of societal benefits derived from nature. Dominant social groups also enact and enforce policies and societal norms that exacerbate social and environmental inequities. Wealthier and predominantly white neighborhoods generally have more green space, more trees, and greater plant diversity than less affluent neighborhoods. In addition, synergies among pollution (e.g., light, noise, chemical), resource distribution, subsidized predators, and non-native species present novel challenges to organisms, which must respond by moving elsewhere, acclimatizing, adapting, or facing local extirpation. These stressors are often stratified according to racial and/or ethnic backgrounds and wealth. Further, intraspecific variation in phenotypic and genotypic traits of urban species may reflect human-induced disturbances. These relationships highlight the potential for both adaptive and neutral evolutionary processes in urban subpopulations to vary across neighborhoods within cities.


Stratification of wealth and property ownership shapes the distribution and management of urban spaces, thus constructing the urban ecosystem. Systemic racism and classism drive urban wealth stratification, emphasizing the need to address inequality-driven environmental heterogeneity in urban ecological and evolutionary studies. Residential segregation and colonial annexation (as well as gentrification and displacement) generate predictable ecological patterns in vegetation, air and water quality, microclimate, soils, and the built environment through the rapid influx of resources to specific areas. Accounting for such processes will allow more accurate estimation of the effect of humans on urban organisms. Deconstructing the complex and nuanced attributes of social inequality in affecting biological phenomena can also inform more equitable and sustainable urban planning solutions that implement anti-racist and justice-centered actions. Racial oppression and economic injustice are jeopardizing urban and global ecosystem health and function. Structural racism and classism are further layered with other inequalities, thus necessitating an intersectional approach to urban ecology. Deeper integration across the natural and social sciences is therefore an urgent priority for advancing our understanding of urban ecosystems and developing applied solutions that promote environmental justice, equity, and sustainability.

Residential segregation and systemic racism have substantial impacts on ecological and evolutionary dynamics in cities.

Government-sponsored policies stratify neighborhoods on the basis of race and class (e.g., through “redlining” in the United States, represented here by the red circle), which results in restricted access to social services and environmental amenities for racial and/or ethnic minorities and low-income communities (red arrows). Habitat quantity and quality tend to be greater in wealthier and predominantly white neighborhoods (green arrows), which leads to variations in ecological and evolutionary processes, underscoring the influence of systemic racism and inequality in driving urban landscape characteristics.


Urban areas are dynamic ecological systems defined by interdependent biological, physical, and social components. The emergent structure and heterogeneity of urban landscapes drives biotic outcomes in these areas, and such spatial patterns are often attributed to the unequal stratification of wealth and power in human societies. Despite these patterns, few studies have effectively considered structural inequalities as drivers of ecological and evolutionary outcomes and have instead focused on indicator variables such as neighborhood wealth. In this analysis, we explicitly integrate ecology, evolution, and social processes to emphasize the relationships that bind social inequities—specifically racism—and biological change in urbanized landscapes. We draw on existing research to link racist practices, including residential segregation, to the heterogeneous patterns of flora and fauna observed by urban ecologists. In the future, urban ecology and evolution researchers must consider how systems of racial oppression affect the environmental factors that drive biological change in cities. Conceptual integration of the social and ecological sciences has amassed considerable scholarship in urban ecology over the past few decades, providing a solid foundation for incorporating environmental justice scholarship into urban ecological and evolutionary research. Such an undertaking is necessary to deconstruct urbanization’s biophysical patterns and processes, inform equitable and anti-racist initiatives promoting justice in urban conservation, and strengthen community resilience to global environmental change.

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