Multiple research groups have investigated the complex, hierarchical structure of spider silk and its amazing strength, extensibility and toughness," says Markus Buehler, associate professor of civil and environmental engineering at MIT. "But, while we understand the peculiar behavior of dragline silk from the 'nanoscale up'--initially stiff, then softening, then stiffening again--we have little insight into how the molecular structure of silk uniquely improves the performance of a web.