Publications
Monitoring war destruction from space using machine learning
Published in PNAS June 8, 2021 118 (23)
With Hannes Mueller, Andre Groeger, Jonathan Hersh, and Joan Serrat
Satellite imagery is becoming ubiquitous. Research has demonstrated that artificial intelligence applied to satellite imagery holds promise for automated detection of war-related building destruction. While these results are promising, monitoring in real-world applications requires high precision, especially when destruction is sparse and detecting destroyed buildings is equivalent to looking for a needle in a haystack. We demonstrate that exploiting the persistent nature of building destruction can substantially improve the training of automated destruction monitoring. We also propose an additional machine-learning stage that leverages images of surrounding areas and multiple successive images of the same area, which further improves detection significantly. This will allow real-world applications, and we illustrate this in the context of the Syrian civil war.
Published in PNAS June 8, 2021 118 (23)
With Hannes Mueller, Andre Groeger, Jonathan Hersh, and Joan Serrat
Satellite imagery is becoming ubiquitous. Research has demonstrated that artificial intelligence applied to satellite imagery holds promise for automated detection of war-related building destruction. While these results are promising, monitoring in real-world applications requires high precision, especially when destruction is sparse and detecting destroyed buildings is equivalent to looking for a needle in a haystack. We demonstrate that exploiting the persistent nature of building destruction can substantially improve the training of automated destruction monitoring. We also propose an additional machine-learning stage that leverages images of surrounding areas and multiple successive images of the same area, which further improves detection significantly. This will allow real-world applications, and we illustrate this in the context of the Syrian civil war.
Working Papers
The Ant and the Grasshopper: Seasonality and the Invention of Agriculture
Review and Resubmit at Quarterly Journal of Economics
| theantandthegrasshopper2022.pdf |
During the Neolithic Revolution, seven populations independently invented agriculture. In this paper, I argue that this innovation was a response to a large increase in climatic seasonality. Hunter-gatherers in the most affected regions became sedentary in order to store food and smooth their consumption. I present a model capturing the key incentives for adopting agriculture, and I test the resulting predictions against a global panel dataset of climate conditions and Neolithic adoption dates. I find that invention and adoption were both systematically more likely in places with higher seasonality. The findings of this paper imply that seasonality patterns 10,000 years ago were amongst the major determinants of the present day global distribution of crop productivities, ethnic groups, cultural traditions, and political institutions.
All Along the Watchtower: Linear Defenses and the Introduction of Serfdom in Russia - With Timur Nathkov
Why did Russia enserf its previously free peasants, just as Western Europe was undergoing the opposite transition? Domar argued that Russia’s low population density would have resulted in a high equilibrium wage, and therefore created the incentives for the nobility to restrict labor mobility, so as to appropriate the agricultural surplus. However, while this explains the cross-sectional pattern, it cannot explain why serfdom was not reintroduced in the west after the Black Death. In this paper I propose a new theory, that argues that serfdom was necessary to ensure that the defense cordon against the Tatar slave raids from the south could be effectively manned. In support of my the- ory I demonstrate a geographic association between serfdom and the sequence of linear defenses employed. I also deploy spatial methods to calculate the optimal invasion routes for Tatars, as well as the optimal defense lines to block the raids. I find that modern patterns of development are significantly correlated with calculated defense lines towards the South, where nomadic raids made the cordon defense necessary, but not towards the West, where invaders had extensive logistical tails and could be effectively parried by blocking only the major roads.
Once Upon a Time in America: the Mafia and the Unions
With Giovanni Mastrobuoni and Marta Troya-Martinez
With the emergence of the Italian-American mafia, which we show was driven by labor unrest and a demand for protection, as well as immigration from Italy, labor racketeering became one of the most profitable criminal activities. The Mafia infiltrated several labor unions, controlling labor and restricting competition. We identify places and industries that were more likely to be infiltrated, and show that in such places individuals of Italian origin climbed up to leadership positions. In response to the likely support of workers of Italian origin, these workers started earning significantly more than other European immigrants. This suggest that the Mafia was not only using violence to control labor but was paying them rents too. In their fight against organized crime, the US passed the 1970 Racketeer Influenced and Corrupt Organizations (RICO) Act. We show that RICO cases, which most likely broke many cartels that were kept in place by the threat of violence, led to subsequent growth in employment, in the number of establishments and even in overall wages. The effects were larger in construction, an industry traditionally prone to mafia influence.
What Have the Romans Ever Done for Us? Water infrastructure and Cultural Diffusion - With Per Fredrik Andersson, Filip Novokmet, Andrea Papadia, Tom Zawisza)
Our multidisciplinary team is combining archaeological and geographical data to investigate the interplay between infrastructure, political power, and cultural assimilation. We have developed a GIS model which areas of the Roman Empire could be provided with water using a surface-level, gravity fed aqueduct, and at what cost. We are currently in the process of generalizing this process to include also the possibility of tunnels and the famous elevated arcades, and combine will combine measure with rainfall data, so as to estimate the overall usefulness of Roman water technology in each province. Our objective is to show the extent to which Roman aqueducts served as a gateway towards pacification and eventual cultural assimilation, by using digitized data on 500,000 ancient inscriptions from an archaeological database, as well as the historical record of provincial revolts.
