Do Co-Worker Networks Increase or Decrease Productivity Differences?

Do labor mobility and co-worker networks contribute to convergence or divergence between regions? Based on the previous literature, labor mobility contributes to knowledge transfer between firms. Therefore, mobility may contribute to decreasing productivity differences, while limited mobility sustains higher differences. The effect of co-worker networks, however, can be two-fold in this process; they transmit information about potential jobs, which may enhance the mobility of workers—even between regions—and this enhanced mobility may contribute to levelling of differences. However, if mobility between regions involves movement costs, co-worker networks may concentrate locally—possibly contributing to the persistence of regional differences. In this paper, we build an agent-based model of labor mobility across firms and regions with knowledge spillovers that reflects key empirical observations on labor markets. We analyze the impact of network information provided about potential employers in this model and find that it contributes to increasing inter-regional mobility, and subsequently, to decreasing regional differences. We also find that both the density of coworker networks, as well as their regional concentrations, decrease if network information is available.

Mapping the Sahelian Space

This chapter examines the geographical meaning of the Sahel and its spatial dynamics. Unlike other approaches that define the Sahel as a bioclimatic zone or as an ungoverned area, it shows that the Sahel is primarily a space of circulation in which uncertainty has historically been overcome by mobility. The first section discusses how precolonial empires relied on a network of markets and cities that facilitated trade and social relationships across the region and beyond. The second section explores changing regional mobility patterns precipitated by colonial powers and the new approach they developed to control networks and flows. The third section discusses the contradiction between the mobile strategies adopted by local herders, farmers, and traders in the Sahel and the territorial development initiatives of modern states and international donors. Particular attention is paid in the last section to how the Sahel was progressively redefined through a security lens.

Navigational experience and the preservation of spatial abilities into old age among a tropical forager-horticulturalist population.

Navigational performance responds to navigational challenges, and both decline with age in Western populations as older people become less mobile. But mobility does not decline everywhere; Tsimané forager-horticulturalists in Bolivia remain highly mobile into their 70s and beyond, traveling on small footpaths to gardens and in pursuit of game and other resources. We therefore measured both natural mobility and navigational performance in Tsimané adults, to assess changes with age and to see whether greater mobility was related to better navigational performance across the lifespan. Daily mobility was measured by GPS tracking, regional mobility through interview, and navigational performance through pointing accuracy and perspective taking in environmental space. Although mental rotation and spatial perspective taking declined with age, mobility and pointing accuracy remained high from mid-life through old age. Greater regional mobility was associated with greater pointing accuracy, suggesting that spatial experience at environmental scales may help maintain navigational performance.