How do Roads Spread AIDS in Africa? A Critique of the Received Policy Wisdom ∗

This paper empirically analyzes the influence of road proximity on HIVinfection using geographical data on road infrastructure and the Demographic and Health Surveys collected in six African countries. Firstly we show that living in proximity to a major road increases the individual risk of infection. This observed relationship is found to be sensitive to the use of the road and to be robust after correcting for potential selection bias related to the non random placement of people. Secondly, our findings reveal that road infrastructure improves the level of HIV/AIDS-knowledge and facilitates access to condoms, providing no support to the hypothesis that HIV-infection is purely due to ignorance and misfortune. Thirdly, we find that the increased risk of infection is driven by a higher likelihood of engaging in casual sexual partnerships that more than offsets the effect of the increased use of condoms

Take the highway? Paved roads and well-being in Africa

Public Goods aim to improve individual welfare. We investigate the causal consequences of roads onwell-being in 24 African countries, instrumenting paved roads by 19th Century hypothetical linesbetween major ports and cities. We have data on over 32000 individuals, and consider both theirobjective and subjective well-being. Roads reduce material deprivation, in terms of access to basicneeds, but at the same time there is no relation between roads and subjective living conditions. Thebenefit of roads in providing basic needs then seems to be offset by worse outcomes in non basic-needsdomains

Mothers and Fathers: Education, Co-residence, and Child Health

International audienc

A Model of Smiling as a Costly Signal of Cooperation Opportunities

OpenAccessInternational audienceWe develop a theoretical model under which “genuine” or “convincing” smiling is a costly signal that has evolved to induce cooperation in situations requiring mutual trust. Prior to a trust interaction involving a decision by a sender to send money to a recipient, the recipient can emit a signal to induce the sender to trust them. The signal takes the form of a smile that may be perceived as more or less convincing, and that can be made more convincing with the investment of greater effort. Individuals differ in their degree of altruism and in their tendency to display reciprocity. The model generates three testable predictions. First, the perceived quality of the recipient’s smile is increasing in the size of the stake. Secondly, the amount sent by the sender is increasing in the perceived quality of the recipient’s smile. Thirdly, the expected gain to senders from sending money to the recipient is increasing in the perceived quality of the recipient’s smile

Smiling is a Costly Signal of Cooperation Opportunities: Experimental Evidence from a Trust Game

We test the hypothesis that "genuine" or "convincing" smiling is a costly signal that has evolved to induce cooperation in situations requiring mutual trust. Potential trustees in a trust game made video clips for viewing by potential trusters before the latter decided whether to send them money. Ratings of the genuineness of smiles vary across clips; it is difficult to make convincing smiles to order. We argue that smiling convincingly is costly, because smiles from trustees playing for higher stakes are rated as significantly more convincing, so that rewards appear to induce effort. We show that it induces cooperation: smiles rated as more convincing strongly predict judgments about the trustworthiness of trustees, and willingness to send them money. Finally, we show that it is a honest signal: those smiling convincingly return more money on average to senders. Convincing smiles are to some extent a signal of the intrinsic character of trustees: less honest individuals find smiling convincingly more difficult. They are also informative about the greater amounts that trustees playing for higher stakes have available to share: it is harder to smile convincingly if you have less to offer.costly signaling; experiment; Smiling; trust game; video