How many people died in the Americas after 1492, and was it mostly disease?

Nobody knows exactly, because nobody knows how many people lived there at the start. Estimates of the pre-colonial Indigenous population range from as low as 8 million to as many as 100 million, though by the end of the 20th century many scholars tended toward about 50 million. These estimates are extrapolations from small bits of data. One much-cited statement from scientists at University College London is that some 90% of Indigenous Americans had perished a century after Columbus, from disease, mass slavery and war.

What killed them is also argued. The causes include Eurasian diseases such as influenza, pneumonic plagues and smallpox; direct violence through war and forced removal; and the general disruption of societies. Scholarly disputes remain over the degree to which each contributed. Some scholars, like Noble David Cook, believe epidemic disease, to which Indigenous peoples had no prior exposure or resistance, was the primary cause. In places such as Mexico in the 16th century, 50-80 percent of the population died from waves of disease brought by Europeans.

Others push back. Andrés Reséndez points out that deadly diseases such as smallpox are not mentioned in the New World until 1519, implying that until then disease played no significant part in the depopulation of the Antilles, where forced labour, brutal punishment and lack of the necessities of life were the initial and major reasons. More broadly, as the Coquille scholar Dina Gilio-Whitaker puts it, recent researchers challenge the idea that disease alone was responsible, pointing also to war, massacres, enslavement, overwork, deportation, malnutrition and the loss of land.