Abstract

We are all familiar with the prototypical elastic instability: the buckling of a slender column under a compressive load. Soft elastic solids, such as rubbers, gels, and biological tissues, are united by their ability to sustain very large shape changes, and consequently undergo a range of more exotic elastic instabilities which sculpt the solids into complicated and unexpected shapes. I will discuss several such instabilities, including fingering in soft solid layers under tension, beading in solid cylinders subject to surface tension, and sulcus formation at the boundary of soft solids in compression. In the second half of the talk, I will discuss a growing pool of evidence that evolution uses these instabilities to sculpt biological organs during development, using as examples the formation of villi in the gut, and the formation of folds on the surface of the human brain.