It’s hard to imagine a human society acting rationally or humanely if mortality levels began reaching catastrophic levels. In the past, societies have been reshaped and at times have nearly crumbled under the weight of a pandemic. It’s possible that, facing mortality rates of 50, 60, or 70 percent—as people who lived through the Black Death did—we might do as they did: turn to religion, change the social structure, blame unpopular minorities and groups, or abandon previous belief systems.