Archeologists use the word industry to describe a classification or assemblage of stone tools. The Oldowan tool industry is the oldest known stone tool industry. It dates from around 2.5 to 1.5 MYA. Because there were several hominins in Africa during this time, it is unclear whether these tools were created and used by H. habilis or by Paranthropus boisei, or by both (Susman 1991). Oldowan tools are fairly crude and primitive in appearance, which can make it difficult to find and identify them in the field. Figure 5.5 An Oldowan tool. This chopper is made of quartzite and dated to the lower Paleolithic period. (credit: Locutus Borg/Wikimedia Commons, Public Domain) Mary Leakey was the first to create a system to classify Oldowan assemblages, basing her classification on utility, or how the tools were used. Later efforts were made to classify tools based on how the tools were made. All Oldowan tools were created by using hard hammer percussion, in which flakes are chipped away from a stone, resulting in a “core”. These cores served as basic tool that could have been used for killing game, cutting meat and plants, and possibly woodworking. Oldowan toolmaking is the earliest evidence of “flint knapping,” a technique that became more complex over time, resulting in more sophisticated tools (Figure 5.6). Figure 5.6 Demonstration of flint knapping, an ancient technique for shaping stones into useful tools. (credit: “Flint-knapping Demonstration” Tonto National Monument/NPS photo/flickr, CC BY 2.0) Handedness, or brain lateralization (i.e., whether one is right-handed or left-handed), is a cognitive development that can be inferred through evidence of the use of a dominant hand in creating and using tools. The use of a dominant hand suggests a possible reorganization of the brain. It is believed that about 90 percent of humans are right-handed, which differs from apes, which are closer to 50 percent. David Frayer (2016), an anthropologist from the University of Kansas, has concluded that the brain lateralization of Homo habilis was more like that of modern human than that of apes. Frayer found striations on the teeth of a 1.8-million-year-old Homo habilis fossil that indicate right-handedness. He concluded that meat was pinched between the teeth and held in place with the left hand, while the right hand cut the meat with a tool. Brain lateralization, increasing brain size, and tool use are just some of the key developments we see in the genus Homo.