If your country is heterogeneous, then you have less social capital

Makes sense, doesn't it? Here’s the abstract.

Motivated by theoretical arguments (see e.g. Putnam, 2007) that assert a negative impact of ethnolinguistic diversity on social capital, this paper aims to provide some empirical evidence on the relationship between the two variables. In particular, using a cross section sample of 68 developed and developing countries, this paper has found a significant negative effect of ethnolinguistic diversity on social capital. Countries with fractionalized ethnic and linguistic groups as captured by both log number of languages and Desmet et al. (2012) and La Porta et al. (1999)’s measures on linguistic diversity tend to have lower levels of social trust, fewer memberships in social organizations, deteriorated social norms and structure, hence, lower overall social capital stock.

if you look at successful countries with high social capital, then they were more homogenous…interesting evidence.