European settlers also began trafficking of African slaves into Colonial America via the transatlantic slave trade. Because of a lower prevalence of tropical diseases and better treatment, slaves had a much higher life expectancy in North America than in South America, leading to a rapid increase in their numbers. Colonial society was largely divided over the religious and moral implications of slavery, and several colonies passed acts both against and in favor of the practice. However, by the turn of the 18th century, African slaves had supplanted European indentured servants as cash crop labor, especially in the American South.