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Researchers find that varying stiffness and speeds at which skin grows lead to ‘mechanical’ formation of inward folds

Scales, hair or feathers typically formed on animals where particular genes were turned on during development as a result of certain chemicals – themselves produced from genes – acting on DNA. This gives rise to a regular pattern.

The dynamics behind this complex process were worked out by Alan Turing, the mathematician and computer scientist.

But it appears the scales on a crocodile’s head are not under such genetic control. Milinkovitch and his colleagues said the scales instead developed because the skin of the face and jaw grew faster than the tissues to which it was attached, and the layers of skin itself had different levels of stiffness. The upshot is the skin folds inward, giving rise to scales with an irregular pattern.

In other words, it is a purely mechanical process.