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A tool is any physical item that can be used to achieve a goal, especially if the item is not consumed in the process. Tool use by humans dates back millions of years, and other animals are also known to employ simple tools. Tools that are used in particular fields or activities may have different designations such as "instrument", "utensil", "implement", "machine", "device," or "apparatus". The set of tools needed to achieve a goal is "equipment". The knowledge of constructing, obtaining and using tools is technology. ==History== Anthropologists believe that the use of tools was an important step in the evolution of mankind.〔Sam Lilley, ''(Men, Machines and History: The Story of Tools and Machines in Relation to Social Progress )'', 1948 Cobbett Press.〕 Humans evolved an opposable thumb — useful in holding tools — and increased dramatically in intelligence, which aided in the use of tools.〔(Primates and Their Adaptations, 2001 ), M.J. Farabee. Retrieved on November 6, 2006.〕 Because tools are used extensively by both humans and wild chimpanzees, it is widely assumed that the first routine use of tools took place prior to the divergence between the two species.〔Whiten, A., J. Goodall, W. C. McGrew, T. Nishida, V. Reynolds, Y. Sugiyama, C. E. G. Tutin, R. W. Wrangham, and C. Boesch. 1999. Cultures in Chimpanzees. ''Nature'' 399:682-685. Panger, M. A., A. S. Brooks, B. G. Richmond, and B. Wood. 2002. Older than the Oldowan? Rethinking the emergence of hominin tool use. ''Evolutionary Anthropology: Issues, News, and Reviews'' 11:235-245.〕 These early tools, however, were likely made of perishable materials such as sticks, or consisted of unmodified stones that cannot be distinguished from other stones as tools. Stone artifacts only date back to about 2.5 million years ago.〔 Also ISBN 0-521-46786-1 (paperback)〕 However, a 2010 study suggests the hominin species ''Australopithecus afarensis'' ate meat by carving animal carcasses with stone implements. This finding pushes back the earliest known use of stone tools among hominins to about 3.4 million years ago. Finds of actual tools date back at least 2.6 million years in Ethiopia.〔Semaw, S., M. J. Rogers, J. Quade, P. R. Renne, R. F. Butler, M. Domínguez-Rodrigo, D. Stout, W. S. Hart, T. Pickering, and S. W. Simpson. 2003. 2.6-Million-year-old stone tools and associated bones from OGS-6 and OGS-7, Gona, Afar, Ethiopia. ''Journal of Human Evolution'' 45:169-177.〕 One of the earliest distinguishable stone tool forms is the hand axe. Up until recently, weapons found in digs were the only tools of “early man” that were studied and given importance. Now, more tools are recognized as culturally and historically relevant. As well as hunting, other activities required tools such as preparing food, “…nutting, leatherworking, grain harvesting and woodworking…” Included in this group are “flake stone tools". Tools are the most important items that the ancient humans used to climb to the top of the food chain; by inventing tools, they were able to accomplish tasks that human bodies could not, such as using a spear or bow and arrow to kill prey, since their teeth were not sharp enough to pierce many animals' skins. “Man the hunter” as the catalyst for Hominin change has been questioned. Based on marks on the bones at archaeological sites, it is now more evident that pre-humans were scavenging off of other predators' carcasses rather than killing their own food. Mechanical devices experienced a major expansion in their use in Ancient Greece and Ancient Rome with the systematic employment of new energy sources, especially waterwheels. Their use expanded through the Dark Ages with the addition of windmills. Machine tools occasioned a surge in producing new tools in the industrial revolution. Advocates of nanotechnology expect a similar surge as tools become microscopic in size.〔(Nanotechnology: Big Potential In Tiny Particles ), David Whelan. Retrieved on November 6, 2006〕〔(Will this Tiny Science Usher in the Next Industrial Revolution? ), Katrina C. Arabe. Retrieved on November 6, 2006〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「tool」の詳細全文を読む スポンサード リンク
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