The Pew Charitable Trust reported this week found that cities with income-diverse neighborhoods offer more economic mobility. Critics quickly cited another study that found diversity undermines community bonds, which is “just natural.” (More)

Limits of Evolutionary Psychology, Part III: Diversity, Inequality, and “Just Natural” (Non-Cynical Saturday)

This week Morning Feature considers the emerging field of evolutionary psychology and its potential impact on public policy. Thursday we saw the common social science bias toward WEIRDness in a recent study on female interaction. Yesterday we looked at “Just So Stories” that presume more than the research has proved. Today we conclude with why progressives must avoid “appeals to nature.”

“The role that neighborhoods and communities play”

A new study by the Pew Charitable Trust found that cities with income-diverse neighborhoods have significantly higher economic mobility than cities with income-segregated neighborhoods:

Consider two children from poor families growing up in the 1970s, one in Boston and the other in the greater New York area. Both families have incomes that are about half the average for their metropolitan areas. When the children become adults, the child raised in New York could expect to have income that is about 7 percent further below New York’s average than the Boston child’s will be relative to the Boston average.
The findings of this report have important implications for policymakers seeking to increase economic opportunity in their states and localities.

First, this analysis underscores the need to move beyond a national approach in the study of economic mobility. The overarching literature has rarely moved beyond the idea that a single level of mobility characterizes the country as a whole. Federal policies relating to education, taxation, and the economy clearly have implications for economic mobility, but regional and local variation in economic and political climates, industry mixes, and demographics could affect mobility as well.[…]

Further, and more importantly for policy leaders, the report’s findings highlight the role that neighborhoods and communities play – separate from the characteristics or choices of families themselves – in the process of economic mobility. Understanding not just that environment matters, but also why, is critical for developing effective interventions.

The Pew study’s results make intuitive sense. People in low-income-only neighborhoods will have fewer upscale social contacts and fewer job opportunities. Such neighborhoods also influence individuals’ decisions, as we saw in our series on why class matters, and more recent studies have proven that poverty impedes brain function, as brilliantly expressed in this essay by a struggling young mother.

“Making the communities less cohesive”

When Richard Florida reported on the Pew Trust study for The Atlantic, a reader quickly cited other research to dispute the Pew findings, including this study by psychologist Zachary Neil and sociologist Jennifer Neil, also reported by Dr. Florida for The Atlantic:

After 20 million-plus simulations, the authors found that the same basic answer kept coming back: The more diverse or integrated a neighborhood is, the less socially cohesive it becomes, while the more homogenous or segregated it is, the more socially cohesive. As they write, “The model suggests that when people form relationships with similar and nearby others, the contexts that offer opportunities to develop a respect for diversity are different from the contexts that foster a sense of community.”

The reader opined:

Economic integration of urban communities comes at a cost of making the communities less cohesive, as the people in those communities tend to associate with those similar to themselves.

“It omits certain complexities that exist in reality”

Well, sort of. The Neils were very aware of the limits of their study, which used computer modeling rather than actual human data:

Statistician George Box famously noted that all models are wrong, but some are useful. This is certainly the case for agent-based models, which strive for parsimony in explaining complex phenomena. In the case of the model we present here, it is “useful” because it demonstrates how the frequently observed negative relationship between diversity and sense of community can emerge from two relatively simple behavioral tendencies, and is “wrong” in the sense that it omits certain complexities that exist in reality.

Most importantly, the Neils explain, they use a single scale for diversity. That could reflect any personal characteristic: race, age, sex, religion, occupation, or favorite sports team. But a single diversity scale can’t reflect all of those personal characteristics unless you assume they all clump together. And some clearly don’t.

Yes, we tend to make friends when we have things in common. But people in an economically diverse neighborhood may bond over shared church attendance, or meet on Sunday mornings to walk their dogs in a local park. They may ride mass transit and become friends because they grumble about the uncomfortable benches at the bus stop. They may not initially guess they have in common, but seeing each other in the home team’s colors might be enough to spark a conversation, where they find they like the same mystery authors.

“On the cover of Duh magazine”

Not surprisingly, many readers assumed the Neils’ paper was about race, and that forming friends with only people who looked like you was natural. As one put it:

Well, this may be news to The Atlantic, but I do seem to recall seeing it on the cover of Duh magazine a few years back.

And yes, if you’re politically conservative, that probably feels true, because conservatives tend to prefer homogenous, closely-knit communities. There is an evolutionary basis for that preference, as Avi Tuschman explained. But the reader comments at The Atlantic are appeals to nature: claiming moral virtue simply because some trait commonly appears in nature.

What’s more, city-dwellers tend to be liberals and prefer diverse, loosely-knit communities and, as Avi Tuschman explained, there’s also an evolutionary basis for that preference.

Moreover, research shows that people in diverse, loosely-knit communities are more likely to find job opportunities. If most of the people you know also know each other – the Neils’ definition of a “cohesive” community – then it’s more likely that either all of you know about a new opportunity, or none of you knows about it. But in an diverse, less cohesive neighborhood, it’s more likely that someone you know will know about that new opportunity because he/she knows people that you don’t.

In an economically diverse community, it’s also more likely a child of poorer parents can find mentors who aren’t trapped in the worldview of poverty. Couple that with the wider access to opportunities that comes with loose ties, and it makes sense that children in economically diverse communities would have greater social mobility than those in economically segregated communities.

The Neils’ study doesn’t disprove the Pew Trust study. Quite to the contrary, the two studies point to the same conclusion: diverse neighborhoods offering more-but-looser ties will significantly increase economic mobility. But you might not find that just by briefly scanning news articles … especially if you’re looking for ‘science’ that confirms what you already believe.

Like all social sciences, evolutionary psychology has its limits. We also need to recognize our own human weaknesses, such as confirmation bias. If the only science you trust is the science that says “Congratulations, genius!” … you’re not doing science at all.


Happy Saturday!