More than .15 per square mile. According to Guns, Germs, and Steel, a population of 4,000 humans living in Tasmania were cutoff from contact with the mainland

More than .15 per square mile. According to Guns, Germs, and Steel, a population of 4,000 humans living in Tasmania were cutoff from contact with the mainland after the Bass Straight flooded 10,000 years ago. In this extreme isolation, they regressed beyond even stone-age technology, including losing knowledge of how to catch fish or start fires. https://books.google.com/books?id=PWnWRFEGoeUC&pg=PA312&lpg=PA312&dq=guns+germs+and+steel+tasmania&source=bl&ots=Ol_5hGxUlS&sig=E9DhyYydJrCYM5ZwdtOt34qQ9I8&hl=en&sa=X&ved=0ahUKEwie4PrR0dnTAhVN62MKHbDhBSgQ6AEIHDAA https://books.google.com/books?id=PWnWRFEGoeUC&pg=PA312&lpg=...