Evolution of abstraction

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A note for Lesson no. 7, "Our Brains Can Create Reality," in Seven and a Half Lessons About the Brain by Lisa Feldman Barrett.
Some context from page 119‌ is:

...as far as we know, humans are the only animal whose brains have enough capacity for compression and abstraction to create social reality.

Scientists are not sure when and how the human brain, with its Five Cs, evolved its capacity for abstraction, but one way to track its evolution through the ages is to follow the evolution of tool use. Around two and a half million years ago, our ancestors created fairly crude stone tools made from carefully chosen and deliberately transported stones, shaped to make a point, with edges for defleshing bone, called Oldowon tools.[1]

By about 1.5 million years ago, our ancestors were making more refined stone tools out of flint, called Achulean tools.[2][3]

To efficiently acquire the skill of Achulean tool-making in a short period of time (rather than years or decades), it is helpful to learn knapping, a technique for flaking bits of stone off a larger stone core. Knapping concepts are abstract, because the details of how to hold the stone that will become the weapon, where to hit the core, the striking angle, and the degree of force all change depending on the specific rock and the size and strength of the toolmaker’s hands. Scientists learned the importance of abstract knapping concepts by observing participants as they were taught to make Achulean stone tools by various instruction methods, including imitation, teaching with gestures, and teaching with verbal language.[4]

Scientists have also hypothesized that our ancestors developed more advanced tool-making in concert with the modern language, which is an efficient way to communicate most things, including abstract concepts.[5]

The neuroarchaeologist Dietrich Stout has observed evidence consistent with this hypothesized link between toolmaking and language. He scans test subjects’ brains before and after learning how to make Achulean hand axes and indeed observes changes in the structure of brain regions that are involved in processing language. Who knew that chipping at pieces of rock would have such an impact on the brain?[6][7][8]

Capacity for compression and abstraction

The capacity for compression and abstraction is necessarily about brain size but not exclusively. The human brain can accomplish compression and abstraction because it's large in absolute terms but also because there have been genetic changes that soup up the wiring and metabolism of neurons in layers 2 and 3 of the cerebral cortex, particularly at the front of the brain.


  1. Lewis, Jason E., and Sonia Harmand. 2016. “An Earlier Origin for Stone Tool Making: Implications for Cognitive Evolution and the Transition to Homo.” Philosophical Transactions of the Royal Society B: Biological Sciences 371 (1698): 20150233.
  2. Beyene, Yonas, Shigehiro Katoh, Giday WoldeGabriel, William K. Hart, Kozo Uto, Masafumi Sudo, Megumi Kondo et al. “The characteristics and chronology of the earliest Acheulean at Konso, Ethiopia.” Proceedings of the National Academy of Sciences 110, no. 5 (2013): 1584–1591.
  3. Lepre, Christopher J., Hélène Roche, Dennis V. Kent, Sonia Harmand, Rhonda L. Quinn, Jean-Philippe Brugal, Pierre-Jean Texier, Arnaud Lenoble, and Craig S. Feibel. “An earlier origin for the Acheulian.” Nature 477, no. 7362 (2011): 82.
  4. Morgan, Thomas J. H., Natalie T. Uomini, Luke E. Rendell, Laura Chouinard-Thuly, Sally E. Street, Hannah M. Lewis, Catherine P. Cross, C. Evans, R. Kearney, I. de la Torre, A. Whiten, and Kevin N. Laland. 2015 “Experimental Evidence for the Co-Evolution of Hominin Tool-Making Teaching And Language.” Nature Communications 6: 6029.
  5. Bickerton, Derek. 2009. Adam’s Tongue: How Humans Made Language, How Language Made Humans. New York: Macmillan.
  6. Hecht, Erin E., D. A. Gutman, Nada Khreisheh, S. V. Taylor, J. Kilner, A. A. Faisal, B. A. Bradley, Thierry Chaminade, and Dietrich Stout. 2014. “Acquisition of Paleolithic Toolmaking Abilities Involves Structural Remodeling to Inferior Frontoparietal Regions.” Brain Structure and Function 220 (4): 1–17.
  7. Stout, Dietrich, and Erin E. Hecht. 2017. “Evolutionary Neuroscience of Cumulative Culture.” Proceedings of the National Academy of Sciences 114 (30): 7861–7868.
  8. Stout, Dietrich, and Nada Khreisheh. 2015. “Skill Learning and Human Brain Evolution: An Experimental Approach.” Cambridge Archaeological Journal 25 (4): 867–875.