The findings seem to suggest the opposite causal relationship. Places with higher wealth and more inudstrialization would have the capital and food production

The findings seem to suggest the opposite causal relationship. Places with higher wealth and more inudstrialization would have the capital and food production to support more people working on cash crop agriculture. The study finds that in places with high slavery investment wages were higher and worker welfare was increasing, while landowner profits were down due to reduced labor availability, suggesting quite strongly that the slavery was compensating for a pre-existing labor shortage. Further, while bad weather could by chance increase slave mortality on crossing, it seems reasonable to assume that wealthier and more technologically advanced areas would be employing better ships and utilizing more effective methods of ensuring their cargo reached their destinations, so crossing mortality can not be taken as an independent variable. As for the geographic connection, it hardly seems surprising that major port cities also became manufacturing centers.