Abstract
It is widely assumed that as populations become more market integrated the 'inner circles' of people's social networks become less densely connected and family-oriented. This 'loosening' of kin networks may fundamentally alter the social dynamics of reproduction, facilitating demographic transitions to low fertility. Few data exist to test this hypothesis. Previous research in urbanized populations has not explicitly measured kin density in ego-networks, nor assessed how market integration influences network structure at different levels of aggregation. Here I analyze the ego-networks of ~2000 women in 22 rural Polish communities transitioning from subsistence farming to market-dependence. I compare how ego-network size, density and kin density co-vary with household and community-level market integration. Market integration is associated with less kin-dense networks, but not necessarily less dense ones, and is unrelated to network size. Declining kin density during economic transitions may be a critical mechanism for the broader cultural transmission of low fertility values.