ABSTRACT
History is the study of the human past. Historians are thus concerned with people’s individual and collective deeds and characteristics and how those things have changed over time. As a species, Homo sapiens has existed for perhaps 200,000 years. The number of individuals to have lived exceeds 100 billion. 1 That leaves historians with a lot of room for study, even if they limit their attention to the 5,000 years or so since the invention of writing.
