In answer to this question there are numerous theories which anthropologists, historians and sociologists discuss. In ancient times, different people groups and regions of the world would specialize in different weapons at different times and in different places. This was due to several reasons, such as the needs of their particular society, whether hunter/gatherer or agrarian, anarchic or imperial, peaceful or violent. Availability of natural resources suitable for manufacture of particular weapons was another determining factor, as was the exposure during peace or war to various technological breakthroughs achieved in other regions. Geography, flora and fauna, climate, etc..., were all factors. Like the throwstick or boomerang, the ancient sling is an example of an isolated weapon (when considered in the context of the Andes mountains). The Inca were an advanced agricultural empire who used the sling extensively. The abundance of suitable llama wool to manufacture slings, and the abundance of stones to use as projectiles were driving forces behind their choice of this weapon. On the other hand, they did not use bows and arrows because of their lack of supply of suitable wood for manufacture in their region. They developed sling braiding to a breathtaking complexity and beauty unparalleled in the modern world, and they became deadly shots, as recorded by their conquistador invaders who claimed to have seen sling stones break swords and kill horses. The history of the world and human cultures is also the history of weapons technological development and its eventual results. Since weapons technology gave an edge in warfare as well as in hunting, an "arms race" which came through the threat and reality of violence was inevitable globally, as it still is today. This is particularly true wherever early states formed, whatever the cause for that might be in various regions. Certain weapons were so powerful and refined that they tended to actually work towards empowering empires, and empires in turn produced these weapons as a means to further their empires.... One empire would tend to rule until the next used superior weapon's technology or tactics to conquer it and rule in its stead. Bows and arrows were a high level weapon technology for ancient man. Ancient empires could divide labor, import materials, enforce slavery, and specialize in making high quality arrows, bows, and strings the way global empires specialize in fighter jets and nukes today.... Lone hunters and tribal peoples were generally not as good at this in most places of the world, and thus their ways of life tended towards being wiped out by the nearby empires which possessed superior ranged firepower. This is certainly not the only factor at play, but the bow attained warfare weapons dominance in most parts of the world due to its high velocity, range, organ piercing power, repeat shot capacity, and easy adaptability to horseback. On the other hand, the bow and arrow doesn't go hand in hand with hunter/gatherer cultures and their diets as much as we sometimes perceive that they do. Although there are exceptions, including the modern Hadza, they were used in a well developed form much more by agriculturally based empires than by hunter/gather groups who wanted more multi-purposed tools. The throwstick or boomerang was never much of a weapons advantage for warfare and people who used it may use it violently but more rarely in a lethal way. In hunting it was an amazing tool which could take game on the run, but in warfare it was easy to dodge unless kept in hand and used as a club. Similar things could be said about the Australian spear thrower. Thus the highest refinements of weapons technology available in Australia left that continent at a relatively basic warfare technology stalemate among the different groups. The rise of empire was not bolstered and encouraged by the bow and arrow as it was elsewhere in the world, nor by the horse. This self limiting technological development, whether geographical, due to cultural preference, or availability of natural resources, preserved a more ancient and enduring way of life among the Aboriginals which was passed down for thousands of years and worked to prevent the formation of centralized empire and their resultant accelerated arms race and conquest. The throwstick was certainly not the only factor, just one ingredient in a list of them which transported the ancient Aboriginal cultures into the 20th century in ancient form, and into their eventual and bloody conflict with European colonization and the deadly modern weapons that came with that. Perhaps somewhat beyond the scope of this website, a brief summary of how different types of societies were formed and later came into conflict can be undertaken below. Human socieities come in many forms but the earliest forms were hunter/gatherer. When family units and individuals compete with each other for natural resources in an uncoerced market of individual personalities and small, self forming and self loyal groups, then violence tends to distribute, counterproductive and self limiting. Cooperation tends to increase as the best overall strategy for success in survival and harmony within the group and with the world around, including other groups. Conflict is avoided as much as possible and sharing is the norm among hunter gatherer peoples because those who don't share don't survive. In harsher environments males tend to dominate more and in gentler environments a more egalitarian culture tends to arise. Yet in all cases, the need for weapons which efficiently kill other humans is relatively limited and warfare is often more a show of force and scary masks than an actual large scale bloody conflict. This is all that is necessary to establish territorial boundaries between differing cultures and peoples, and when these guidelines are not followed, increasing violence tends to self correct in time on smaller scales. Violence is a part of all animal and human life to one degree or another. The formation of the earliest states was a departure from small group forms of early human cultures and represent a move towards coercion for the benefits it provided those who were able to coerce. This move created compromises with health, liberty, labor, and increasing violence, but it created the benefits to some of being able to reap the rewards of other people's labor and thus the incentive for state formation. The formation of early states was seemingly bolstered by religious or superstitious loyalty as well as availability of new weapons technology, certain aspects of geography, domestication of horses, values of controlling various natural resources in a given region, etc.... Coercive forms of human society which base themselves on slavery, conquest and forced labor and taxation, tend to create boom and bust cycles of expansion and collapse. Empires and those who support them rise and fall in their cyclical attempts to dominate as far as possible beyond the limits of harmony while maintaining it as much as possible at the same time. While violence and warfare of one level of intensity or another is common to most all human cultures, those cultures which set their sites on conquest are of an opposite survival strategy of those who aim at harmony. Their respective technologies are different to each other as well, even if both fall into the weapons category. Conquest has costs and limits just as harmony does, and it always drives more and more conquest because it must in order to maintain a competitive empire against those who don't want to join or who in turn form competing empires in order to defend themselves against the former. Yet when empire grows to its limits and the coercion needed to maintain it are too much for humans to bear further, it naturally falls. This boom and bust cycle in turn, re-seeds the future empires which arise in the place of the previous ones, out of the ashes of their cultures and basic values. In each generation of boom and bust the technology, values and tactics are passed on and increase in efficiency. They are resurrected under a new structure which rekindles human hope and loyalty and starts the cycle again. The eventual end of coercive, non-harmonized culture is the exploitation of all things available to exploit, until no resources are left for survival. By contrast with this, non-coercive societies maximize natural resources and exclude the conquest values of empire and the huge costs of slave labor. The dying out of throwsticks was the dying out of a world in which simple tools were all that was needed to live in exchange for a world in which technology would form an arms race that lead to the potential for the destruction of all natural resources everywhere. Regardless as to the answers to any debate on these subjects, the Aboriginal boomerang truly is a brilliant and fascinating relic. It stands as a symbol of personal independence and a more simple world and time. Ironically, though something of "primitive" origin, it actually exhibits flight characteristics which make it seemingly defy the laws of gravity. Modern physicists cannot decode all of its secrets and only a few people on the planet have learned how to properly tune them. So the throwstick's true brilliance and complexities, passed down through the generations from father to son are a reminder that "primitive peoples" were not really primitive at all. In fact it was the primitive thinking which classified them as "primitives" which led to their murder and even their being stuffed and placed in museums along side their throwsticks. They were advanced thinkers who were set in different circumstances from the dominant ones of more recent history. Throwsticks are now a great way to connect with the outdoors, and with the ways of life and skills of the past.