Bruce Cummins for U.S. Navy / Wikimedia Commons

The surprising and complex role that segregation plays in increasing a neighborhood's social capital.

I’ve long argued for the advantages of a diverse neighborhood. On the most basic level, diversity is required to attract the wide range of creative talent that drives innovation and economic growth. But it’s also the case that diversity can at times be stymied by the sorting of different groups into separate areas, undermining the very mixing required for those things to happen.

Last year, I wrote about a 2014 study by sociologist Zachary Neal and psychologist Jennifer Watling Neal, which found that diversity leads to just this kind of troubling separation and self-segregation. In a new study, “Making Big Communities Small,” Neal focuses on how this dilemma might be overcome, starting with the incredibly useful and important—but often forgotten—distinction made by Harvard’s Robert Putnam about two kinds of social capital.

On the one hand, there is “bonding” social capital, encapsulated in the extremely close relationships of tight-knit communities. This is the type of social capital that can lead to self-segregation of different groups. On the other hand, there is “bridging” social capital, the kind that bridges across different groups. This is the kind of social capital that can overcome self-segregation and build connective fiber between groups.

My own research with Brian Knudsen has found that bonding social capital is not only negatively associated with diversity, but with innovation as well. In contrast, bridging social capital is associated with both diversity and higher levels of innovation. Most cities are high in one or the other, meaning that they are either tightly-knit and strongly tied but homogenous and not innovative, or socially disconnected, diverse, and innovative. But, as Neal aptly puts it, the real challenge for our cities is how to enable both types of social capital and the good things that flow from them.

Computer-simulated communities

To get at this, Neal develops agent-based computer models to simulate the relationship between a community’s behavioral characteristics and its potential for both bridging and bonding social capital. These models allow Neal to investigate how individual behaviors, like the tendency to bond with someone with shared characteristics, relate to larger social phenomena—something that would be difficult to measure in real life. Overall, Neal ran more than 50,000 individual simulations.

Take a look at the chart below, which shows how these simulations turned out across the dimensions of diversity and segregation. There are communities across all patterns—some have high diversity and high segregation, others are low on both. The black and grey houses on the chart represent two types of people that reflect a variety of demographics, such as race, religion, ethnicity, or social class. On the chart, both black and grey houses are interspersed in areas with low segregation, but tend to cluster together by color in areas with high segregation, and especially in areas with both high segregation and high diversity.

But what happens when Neal adds the dimensions of bonding and bridging social capital?

On the figure below, the left panel shows a network with high levels of diversity and segregation. Relationships in this community are driven by strong tendencies toward proximity (the tendency of people to bond with those nearby) and homophily (the tendency of people to bond with others like themselves). This means that although highly diverse, segregated communities have plenty of bonding social capital, they lack bridging ties between groups.

In contrast, the network with low levels of diversity and segregation (shown in the middle) has weak levels of proximity and homophily, but is filled with bridging social capital. Although the network is relatively homogenous, the report describes it as an “integrated community where nearly everyone (same or different, near or far) is considered a potential contact.”

The network on the right has high levels of diversity and segregation, and a strong tendency toward proximity and homophily. Unlike the other networks, this one allows for both bridging and bonding social capital. “Although residents in this community tend to form bonds within their own group, thereby facilitating the development of a sense of community,” Neal writes, “they also form occasional relationships with members of other groups, thereby facilitating the sharing of information and diverse perspectives.” Neal dubs these communities with lots of bonding and bridging social capital “small-world networks.”

Creating small-world networks

Neal then looks for where these small-world networks might form given all of the experimental conditions (diversity, segregation, homophily, and proximity), as shown on the following heat maps. Darker shades on the maps indicate areas with a greater potential for developing social capital.

Although the heat maps are a bit complicated, their findings are relatively straightforward. First off, communities with weak behavioral tendencies (i.e. proximity and homophily) have less potential to form social capital. Surprisingly, this potential is higher in communities with high levels of diversity. Segregation seems to matter less—the potential to form social capital is fairly equal in both high-segregation and low-segregation communities—although areas with high levels of segregation and either strong homophily or strong proximity do have greater potential.

“At first glance, this may seem counterintuitive that segregation is important for social capital,” Neal says in an email. “But, it is important to remember that segregation has many faces. The pernicious racial residential segregation that has plagued American cities for more than a century is one form, but so too is the ethnic enclave that helps immigrants find a foothold and the historically black colleges and universities that incubate some of the country's best students and scholars.”

The ideal community

Ultimately, diverse, segregated communities with a strong (but not absolute) tendency toward homophily are the most conducive to social capital development. In even simpler terms, the ideal community is big and diverse, but “feel[s] small and familiar.” Under these conditions, residents tend to seek out individuals like themselves, giving them a sense of belonging and security, but are open to different viewpoints, promoting creativity and new social relationships.

Of course, this ideal “small-world network” is more likely to exist in a computer simulation than in real life. As Neal’s previous research has shown, it’s rarely the case that the most diverse neighborhoods are also the most cohesive. But while diversity and community may be incompatible on their own, this new study shows that there are ways to make room for bridging social capital without sacrificing the benefits of a tight-knit community.

In the end, Neal says via email, “the city is a patchwork of neighborhoods and districts, each staked out by a particular demographic group, or earmarked for a particular activity, that gives it its unique character. But, in a vibrant city—the kind of place that [sociologist Robert] Park, or later Jane Jacobs so deeply valued—there are many different kinds of patches, and their boundaries are messy and permeable.”

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