And then 10,000 years ago the glaciers melted, sea level rose, and Tasmania became cut off from mainland Australia by Bass Straits, which are really rough waters. In addition, the watercraft of the Tasmanians were wash-through rafts that got waterlogged and sank after about a dozen hours. The result was that the boats of the Tasmanians could not reach Australia, and the boats of the mainland Aboriginal Australians could not reach Tasmania.

Thus, for the last 10,000 years the Tasmanians represented a study of isolation unprecedented in human history except in science fiction novels. Here were 4,000 Aboriginal Australians cut off on an island, and they remained totally cut off from any other people in the world until the year 1642, when Europeans "discovered" Tasmania. What happened during those 10,000 years to that isolated 4,000-person society? And what about nearby Flinders Island, which originally supported a population of 200 cut-off Aboriginal Australians? — what happened to that tiny isolated society of 200 people during those 10,000 years?

When Europeans discovered Tasmania in the 17th century, it had technologically the simplest, most "primitive" human society of any society in the modern world. Native Tasmanians could not light a fire from scratch, they did not have bone tools, they did not have multi-piece stone tools, they did not have axes with handles, they did not have spear-throwers, they did not have boomerangs, and they did not even know how to fish. What accounts for this extreme simplicity of Tasmania society? Part of the explanation is that during the 10,000 years of isolation, the Aboriginal Australians, who numbered about 250,000, were inventing things that the isolated 4,000 Tasmanians were not inventing, such as boomerangs. Incredibly, though, archeological investigations have shown one other thing: during those 10,000 years of isolation, the Tasmanians actually lost some technologies that they had carried from the Australian mainland to Tasmania. Notably, the Tasmanians arrived in Tasmania with bone tools, and bone tools disappear from archeological record about 3,000 years ago. That's incredible, because with bone tools you can have needles, and with needles you can have warm clothing. Tasmania is at the latitude of Vladivostok and Chicago: it's snowy in the winter, and yet the Tasmanians went about either naked or just with a cape thrown over the shoulder.

How do we account for these cultural losses and non-inventions of Tasmanian society? Flinders Island was even more extreme — that tiny society of 200 people on Flinders Island went extinct several millenia ago. Evidently, there is something about a small, totally isolated human society that causes either very slow innovation or else actual loss of existing inventions. That result applies not just to Tasmania and Flinders, but to other very isolated human societies. There are other examples. The Torres Strait islanders between Australia and New Guinea abandoned canoes. Most Polynesian societies lost bows and arrows, and lost pottery. The Polar Eskimos lost the kayak, Dorset Eskimos lost dogs and bow drills, and Japan lost guns.