It seems quite plausible to me. Think of it in terms of information theory. Each person is an unreliable channel, but there are hundreds or thousands operatin

It seems quite plausible to me. Think of it in terms of information theory. Each person is an unreliable channel, but there are hundreds or thousands operating in parallel. The net result is a reliable information transmission channel that stretches back many, many years. As I understand it, the Aborigines have a strict oral tradition, so the passing down of these stories isn't a casual chat over a meal, but a formal education, where accuracy is paramount. Under these circumstances, the reliability of each individual ancestral line goes up, so when they are all operating in parallel, I'd expect the error rate to be quite low, errors in each generation being corrected by a majority vote.