Concern for the rights of animals dates back to at least the nineteenth century, but the modern animal rights movement emerged in the 1970s, initially in Britain. It can be distinguished from a more moderate concern for animal welfare, both in terms of objectives and strategy. Reasons for the rise of the animal rights movement include factors such as affluence, changes in the occupational structure, and the influence of gender that are only indirectly related to the public's concern for animals and what is done to them. More specific explanatory variables include the intellectual ballast provided by academic philosophers, and the greater awareness of what is done to animals and the ways in which they can suffer.