The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 19 No. 2 • February 2016

Oh, no, THIS couldn’t be, could it?

Crumpled Paper As a Model for Cortical Folding in Mammalian Brains

Phrenology is awfully strange and we know of no non-BS scientific papers to go with it.

Here is another view of brain folding that seems pretty weird, too, but researchers have some experimental evidence for their hypothesis.

Scientists have developed a mathematical model for what it looks like when the brain folds and it looks like... crumpled paper (Mota, 2015). The illustration in the commentary (Striedter, 2015) on the study showing the paper ball when crumpled, then expanding into its final folded form has the caption: “Folding increases with paper size, thicker paper has fewer folds. An analogous scaling rule applies to cortical folding in mammalian brains.”

The researchers here “provide a novel mathematical description of how the degree of neocortical folding in mammalian brains varies with other biological parameters, notably cortical thickness and surface area, and they offer the crumpling of a paper ball as a physical model to explain the observed scaling rules.” (Striedter, 2015). “For species with folded cortices (such as the human brain), total surface area increases faster than the exposed surface area (i.e., the slope is substantially greater than 1) [whereas the slope is 1 in species, such as rats and mice, that have smooth cortices].” Interestingly, whales and dolphins have more cortical folds than other mammals with the same cortical surface area (Striedter, 2015).

The researchers (Mota, 2015) crumpled paper balls to determine how the balls relaxed after being crunched. The result was consistent with the general scaling law as seen in the folding neocortex. As the commentary (Striedter, 2015) on the paper notes, “[t]he principal problem with the paper ball analogy is that it describes the folding of a structure that no longer grows, whereas the cortex folds during development.”


  • Striedter and Srinivasan. Knowing when to fold them. Science. 349:31-2 (2015).
  • Mota and Herculano-Houzel. BRAIN STRUCTURE. Cortical folding scales universally with surface area and thickness, not number of neurons. Science. 349:74-7 (2015).

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