The historiography of disease and medicine in colonial India has tended to concentrate on epidemic diseases and particularly those that have produced the greatest political upheavals. On the assumption that epidemic crises expose latent social tensions, historians have tended to treat epidemics as ‘windows’ through which to observe broader social and political trends.
The history of narcotics in Asia in the last century and a half has been the subject of considerable controversy and significant revision over the last 20 years or so.
The greatest indictment of the hard-driving slave system in the 18th-century British Caribbean was that the enslaved population never achieved natural population increase (except briefly in Barbados but only by 1810). Abolitionists seized on the failure of slave populations to thrive as a sign that slavery was immoral.
People down on their luck fleeing to the colonies on the first available ship is a mainstay of 19th century fiction. It was a convenient way for an author to either get rid of an unnecessary character, or to bring a surprise new person into the narrative mix with dramatic effect.