The continent of Australia suffers from a dearth of domesticable plants and animals. As pointed out by Jared Diamond (and others), Australia has produced the total of one plant  which is become a significant food crop: the macadamia nut. Tasty as those nuts are, the basis of an agricultural civilization they do not make. For this reason, Australia was the only habitable continent where the inhabitants did not develop major farming societies before European arrival . There were other factors which inhibited the development of a farming society in Australia, such as the extreme aridity of much of the continent, and irregular droughts even in the fertile areas. Nevertheless, the lack of domesticable crops and animals was a substantial restriction on the development of farming societies in Australia. Since farming was not practical, the large majority of Australia’s pre-European population lived a hunter-gatherer lifestyle. The population density was quite low in comparison to most of the world, even in the more fertile areas. While estimates of the pre-European population of Australia are considerably varied, it seems to have been no more than a million, possibly less. The demographic effects of European colonisation were devastating; a combination of disease, warfare and other factors reduced the indigenous population to somewhere around 100,000 (again, estimates vary) by 1900. While the population has recovered somewhat since that time, Aboriginal and Torres Strait Islanders still form a small minority of Australia’s population; about 450,000 or 2.4% of the total population as of the 2001 census. However, it seems perfectly plausible to find a way to have a much larger pre-European indigenous population in Australia. In nearby New Zealand, the Maori had a farming society based around only one domesticated crop – the kumara or sweet potato. They still supplemented their diet with a wide variety of wild plants and with hunting, but the kumara formed a major component of their diet, acted as a food store, and allowed the establishment of a farming culture. In Australia itself, there many land management practices and a wide variety of plants which were harvested and sometimes replanted. But due to the various characteristics of these plants, none of them turned into a truly domesticated crop, although there are some recent efforts along those lines. In its native crops, Australia notably has several species of yams, which in other parts of the world were turned into domesticated crops. The Australian varieties (Ipomoea costata and several species of Dioscorea) weren’t fully domesticated, although they were certainly harvested and re-used. By a fluke of biology, Australia lacked any species of yams which could be quickly domesticated . This being alternative history, let’s roll the dice again. *Australia has a new plant species when the first Australians arrive. Call it Dioscorea chelidonius, the Red Yam. Like other yam species, D. chelidonius is a perennial vine which produces an edible (and very tasty) tuberous root as a food store. In its wild state, D. chelidonius produces tubers which produce up to 1 kg of edible material. Like those of other yam species, the tubers of D. chelidonius can be stored without refrigeration for up to six months; very handy in an environment where food is often scarce. They can be eaten raw (like some, but not all OTL Australian yam species) but are most preferred when roasted. Although sweet, they are still quite healthy, and will provide a substantial proportion of a person’s daily nutritional intake. D. chelidonius grows wild in the Murray River valley, in (OTL) southern New South Wales and northern Victoria. It is quickly harvested by the first Australians when they arrive, and eventually it will be domesticated. Even with its more favourable properties, this process of domestication will still take some time. But by around 1,500 years ago, a domesticated version of the Red Yam has been developed in northern Victoria. Many more breeds will be developed to suit local conditions, and the Red Yam spreads throughout much of Australia. Trade contact will eventually bring it is far west as the fertile areas of south-western Australia (around Perth), and north as far as southern Queensland. D. chelidonius is naturally a subtropical, not tropical species, and it will not readily grow much further north than the Tropic of Capricorn. It will take over a thousand years of selective breeding before the first varieties of the Red Yam are developed which can grow in tropical conditions, and these will spread into northern Queensland over the next few hundred years. Now, having the grand total of one (1) major domesticated crop will place considerable limitations on the development of farming societies in *Australia. Much like contemporary Maori culture in New Zealand, there will still be a need for protein in the diet, which has to come from hunting in one form or another. The Murray Valley will probably see much more expanded eel-farming, not just Red Yams. It’s quite possible that some other Australian native crops will start down the road to domestication; without the Red Yam as a “founder crop”, no society in OTL could put the effort into domesticating them effectively . Macadamias will almost certainly be domesticated, for instance. But if these crops are domesticated at all, they will be only a relatively small part of the daily calorie intake of the farmers; most of that will come from Red Yams. So, given this premise, what sort of farming societies are likely to develop in *Australia? There are still several limitations. Intermittent droughts will still be a part of life. There’s no handy large domesticable animals, so no beasts of burden. But one thing’s for sure: the population of *Australia will be a lot higher. There will be established villages and towns all along the east coast and in the southwest, although probably not much in the way of large cities. By the time the first wandering Dutchmen sight the western coast, the total population of *Australia is going to be around 5 million. Even assuming Europeans colonise the continent, and allowing for the spread of diseases and warfare, the *Aboriginal population is going to bottom out somewhere around 1 million people and recover from there. Depending on how heavily the continent is colonised, the *Aboriginals may not be the majority of the population, but they’ll certainly be a significant minority. Thoughts? Jared --  To be nitpicky, there’s two species of commercially exploited macadamia nuts, but the differences between them aren’t significant for these purposes.  There were some farming societies in Australia, such as communities in parts of modern Victoria who were eel and yam harvesters. The Aboriginal peoples used a complex system of land management (usually called “firestick farming”) to sustain their food supply. But without domesticated crops, their population density remained relatively low.  Some of the yam species may have been domesticated eventually, particularly those in modern Victoria which were associated with sedentary eel-farming communities. But they weren’t easy to domesticate, and it looks like it would have taken a while longer.  There are a number of Australian native plant species whose potential is now being explored; they were harvested wild by the Aboriginal peoples but are not easily domesticable.