Anthropology is divided in two: "biological" anthropologists take evolution and biology seriously and see themselves as scientists, while other types (most notably "cultural") are much within the tradition of postmodernism, and don't aspire to do science (or only pretend to). These second kind aren't concerned much with communicating objective truth (because they don't believe in that); their politics informs their work to a great extent on average.
I don't know which kind Salmond is since I don't know her work, but it's entirely possible to collect all first-hand accounts from pre-$SOME_YEAR and search them for references to how children were treated. Then, assign each one a score based on some measure of how well the children were treated (note: "how well" is in direct reference to the moral system that modern Westerners have, and Salmon takes the same stance without mention in the article). Look at your data. This'll tell you how the people writing thought of it. You should probably also model year of writing and what that means for the writer's baseline, at minimum.
Either way it's interesting. Thanks for sharing!