The pandemic economic crisis, precautionary behavior, and mobility constraints: an application of the dynamic disequilibrium model with randomness

This article analyzes the economic impact of the pandemic, providing insights into the consequences of alternative policies. Our framework focuses on three key features: (i) COVID-19 is a sectoral shock of unknown depth and duration affecting some sectors and technologies more than others; (ii) there are constraints in shifting resources across sectors; and (iii) there is a high level of uncertainty about the disease and its economic aftermath, inducing a high level of precautionary behavior by some agents and leading to others facing more severe credit constraints. Because of macroeconomic externalities, precautionary behavior exacerbates the downturn, and even sectors where COVID-19 does not directly affect consumption or production may face unemployment. Multipliers associated with different government expenditure programs differ markedly. The article describes policies that can mitigate precautionary behavior, leading to reduced unemployment. Greater wage flexibility may lead to increased unemployment. The precautionary behavior is the antithesis of equilibrium behavior, suggesting that standard equilibrium approaches may not provide the appropriate framework for analyzing the pandemic: individuals know that they don’t know the future, that existing and newly made contracts and plans may be broken, and that they need to be able to respond to these unknowable contingencies.

Enamel hypoplasia and dental wear of North American late Pleistocene horses and bison: an assessment of nutritionally based extinction models

Approximately 50,000–11,000 years ago many species around the world became extinct or were extirpated at a continental scale. The causes of the late Pleistocene extinctions have been extensively debated and continue to be poorly understood. Several extinction models have been proposed, including two nutritionally based extinction models: the coevolutionary disequilibrium and mosaic-nutrient models. These models draw upon the individualistic response of plant species to climate change to present a plausible scenario in which nutritional stress is considered one of the primary causes for the late Pleistocene extinctions.In this study, we tested predictions of the coevolutionary disequilibrium and mosaic-nutrient extinction models through the study of dental wear and enamel hypoplasia of Equus and Bison from various North American localities. The analysis of the dental wear (microwear and mesowear) of the samples yielded results that are consistent with predictions established for the coevolutionary disequilibrium model, but not for the mosaic-nutrient model. These ungulate species show statistically different dental wear patterns (suggesting dietary resource partitioning) during preglacial and full-glacial time intervals, but not during the postglacial in accordance with predictions of the coevolutionary disequilibrium model. In addition to changes in diet, these ungulates, specifically the equid species, show increased levels of enamel hypoplasia during the postglacial, indicating higher levels of systemic stress, a result that is consistent with the models tested and with other climate-based extinction models. The extent to which the increase in systemic stress was detrimental to equid populations remains to be further investigated, but suggests that environmental changes during the late Pleistocene significantly impacted North American equids.