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Oops, hair is keratin not collagen. The two are similar though not identical. Keratin is even longer, contains sulphur, and are even more tangled

"The basic unit of hair is a long strand of...

NG was oversimplifying. Three collagen molecules (which are already pretty large compared to the fin of the blade) are twisted into longer fibrils. These molecules are staggered within the fibril,...

Edit: the following is wrong - human hair is made of keratin, not collagen. Perils of posting under the influence. The truth, however, is even worse for the "sliding between molecules" theory. See...

Think snowplow blade.