Titin is one of the proteins that make up the muscles of all vertebrates; it is an elastic protein that acts as a spring by refolding and returning to its original state. “Protein evolution has been studied from many points of view: its thermal stability, function and structure, but no one had ever studied the evolution of the mechanical properties of a protein. For titin this is a particularly appropriate approach given its function,” said Pérez-Jiménez.