Great historical changes are often conceived of as being brought about by the genius and tenacity of great men, or occasionally women, but Jonathan Kennedy argues in his book “Pathogenesis: A History of the World in Eight Plagues,” that germs are largely responsible for everything from the decline of the Neanderthals to the current poverty of sub-Saharan Africa. His quick history of the world from the Paleolithic to the present day offers a different lens to view many of the big events of the past. Some of Kennedy’s conclusions are mere speculation, like his idea that deadly plagues in the Roman empire led to the swift rise of Christianity. In the midst of so much death, he argues, the new religion offered a more enticing view of the afterlife than paganism. Most of his observations are bolstered by more historical research and are more convincing. In showing how pathogens helped the Spanish conquer Central and South America, Kennedy explains that European diseases including smallpox and measles killed or incapacitated most of the native population, which had no immunity to the previously unknown germs. One outbreak in 1545 alone is estimated to have killed up to 80 percent of the Indigenous peoples of Mesoamerica. The death and destruction also accelerated their religious conversion as many of the remaining Indigenous peoples, along with the Spanish, saw it as proof that the Christian God was superior, Kennedy argues. On the other side of the Atlantic, Kennedy explains how resistance to infectious disease – especially the malaria and yellow fever prevalent in parts of sub-Saharan Africa – boosted the slave trade. Disease-resistant Africans were less likely to die on the new world plantations than Europeans, and much of the native population had already been wiped out. The subsequent association of Africans with slavery contributed to the ideology of white supremacy that continues to impact the way African Americans are treated today, Kennedy argues. The presence of malaria and yellow fever also prevented Europeans from colonizing the African interior, but only for a time. That changed when quinine was discovered to help prevent death from malaria. But because the rates of death and disease were still high, the colonies attracted desperate and ruthless individuals with a desire to make a quick fortune and get out. It was disease, Kennedy argues, that helped create the harshly extractive colonial economies in places like the Congo, the repercussions of which are still felt in the extreme poverty of those countries. Poverty, including in wealthy countries like the United States, is a sort of modern plague, killing millions each year with both infectious disease and non-communicable diseases like diabetes, Kennedy argues in the final chapter. These poverty-associated health problems, in turn, have been associated with higher death rates during the COVID-19 pandemic. Kennedy ends with a passionate plea for public health expenditures to eliminate disease.