The Science of Stones

Stone tools are usually associated with cavemen and primitive tribes. The thought of using tools made of rock in a modern setting is laughable to the general public. Yes, technology was not where it is today, but it doesn’t make those populations any less capable than ours. After watching a demonstration of flint knapping by Dr. Lucy Johnson on Monday, it’s obvious there’s a lot more involved in creating a stone tool than anyone would think.

Chipping a stone is a science in itself that requires many years of experience and experimentation. It’s not a natural or easy skill to acquire. Each tool with a different purpose requires a different process to create it. The toolmaker must be focused and think about how the other side of the rock will be altered as they take flakes off—a mistake can’t be fixed very easily. The creation of these tools follows the same path of creation for the tools and technology we have today. We create prototypes, test them and make adjustments to make the tool as efficient as possible just like the people using stone tools.

When most people think of stone tools they usually limit this category to arrowheads, but really there is a huge variety of stone tools. Each of these tools needs to be made from the right kind of stone to ensure it is effective. This would require some basic geological knowledge—it certainly wasn’t a random choice of rock. These toolmakers would have to find the right kind of stone and know where they could find it. They didn’t just pick rocks up off the ground and begin to use them. These ancient toolmakers deserve more recognition than the modern day public gives them.

This illustration of stone tools found in Goat Bluff Cave shows the variety of the stone tool category.

This illustration of stone tools found in Goat Bluff Cave shows the variety of the stone tool category.

There are also a lot of ways to shape a rock and with each of these techniques there is a requirement to know how each type of rock will react. The “simple” arrowheads people find and collect are actually very complex. They must be properly balanced and shaped to fit the arrow so that it flies correctly. And multiple arrowheads must be made almost identically so that the shooter knows how the arrow will fly when they let go of the string. This is a much more involved process than the stereotype of hitting two rocks together.

Anthropologists at George Washington University study  the art of flint knapping.

Anthropologists at George Washington University study the art of flint knapping.

Projectile points also have a lot more to say than modern people think. There are so many variations in the characteristics to study. There are so many reasons a tool could look the way it does due to purpose, culture and environment. To today’s world a stone tool may be insignificant, but to archaeologists they are incredibly important in understanding how people of the past are just like us. There is always a meaning and a story behind these shaped rocks left behind years ago.


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An Inseparable History: The Coevolution of Stone Tools and the Human Hand


In thinking about the 2.6 million year history of stone tools, we often discus the ways in which hands shaped stone; but how did the tools they made shape the hands we use today?

Not surprisingly, the ability to make stone tools had a huge effect on the anatomy of the human hand. Individuals whose hands were better suited to making tools were better able to hunt and protect themselves; this made them more evolutionarily fit (able to produce more offspring), leading to an eventual proliferation of the genes involved in the better hand formation. So when stone tools went from simple banged rocks to complex hand-axes around 1.7 million years ago, this reflected not only an intellectual step but a biological one.

An artist's rendition of a member of the species Homo habilis making a tool of the Oldowan type.

An artist’s rendition of a member of the species Homo habilis making a tool of the Oldowan type.

Before this new technology, the fossil record shows that hominin hands had primitive vestige structures. Although Homo habilis (named the “toolmaker” because of the primitive Oldowan tools found in associated strata) had more advanced hands than those of their predecessors the australopithecines, they were not fully modern. Their fingers had a gentle curve like those of the austrolopithicines, and their wrist morphology resembled that of a part-time arboreal species. Despite these primitive traits, the more modern proportions and joint connecting the finger bones to those of the palm allowed Homo habilis to be credited with the invention of stone tools.

For a long time, the hand’s evolution from 1.7 million years ago (when Homo erectus first shows up in the fossil record and shortly before Homo habilis disappears from it 1.4 million years ago) to about 800,000 years ago was a mystery to paleoanthropologists. Hominin fossils are a rare find at best, and small finger bones especially are easily broken in the millennia they spend in the soil before being excavated. Stone tools, on the other hand, are much more easily preserved. During this almost 1 million year gap, stone tool technology advanced greatly, enough to warrant a new name – Acheulean industry. But what morphological difference had made this advancement possible?

Hand axes of the Acheulean type.

Hand axes of the Acheulean type made and used by the species Homo erectus.


A recent discovery has shed some light on this question. In 2010, a team of paleoanthropologists led by Fredrick Kyalo Manthi of the National Museums of Kenya found what appeared to be a finger bone in northern Kenya. It was identified as a third metacarpal, the bone that connects the middle finger to the wrist. Using isotope analysis, it was dated to 1.4 million years ago and attributed to the species Homo erectus. What’s  interesting about this bone is the small bump at its base – the styloid – a feature found in modern humans. What seems like a small structural change has huge implications; the styloid helps stabilize the wrist, increasing griping power between the thumb and forefinger. This change was instrumental in the ability to make finer, more precise percussions to the core, resulting in more fine-tuned tools with which Homo erectus became the first multi-continental hominin. None of this would have been possible without the mutual selective pressure between early humanity and its tools.



Reardon, Sara. “Stone tools helped shape human hands.” New Scientist, 11 April 2013.

University of Kent. “Stone tools influenced hand evolution in human ancestors, anthropologists say.” ScienceDaily, 8 Mar. 2011.

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Hand ax image URL:

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Works Cited

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Crabtree, Donald (January 1971). Experiments in Flintworking. Idaho State University Museum.

“Firing a Flintlock Pistol.” YouTube. YouTube, 06 June 2013. Web.

“Flintknapping – Beginners Part 1.” YouTube. YouTube, 27 Nov. 2009. Web.

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“Frontier Fire Methods Part 2 Fire By Flintlock.” YouTube. YouTube, 08 Apr. 2013. Web. <>.

“Harry Oda, Master Flintknapper, Flintknapping Demo (part 1).” YouTube. YouTube, 22 Sept. 2012. <>.

“Knapping.” Wikipedia. Wikimedia Foundation, 16 Oct. 2013. Web. <>.

“Untitledpercussion Obsidian Blade 0001.” YouTube. YouTube, 18 June 2009. Web.<>.