Structural reciprocity is a design concept in which different load-bearing elements in a design support each other along the length of the element, allowing for an even distribution of weight across the structure rather than strictly at the ends. Early civilizations demonstrated knowledge of this concept through their homes, even if they had not formally named it yet. For instance, Neolithic civilizations constructed pit dwellings built of structurally reciprocal elements as early as 10,000 to 4,500 BCE. Additionally, Eskimo tents and and teepees constructed by Native Americans also used structural reciprocity in their design. During the reign of Julius Caesar, this concept was translated to infrastructure through the construction of a bridge that spanned the Rhine River composed of interlocking wood. The ancient Chinese also used structural reciprocity by weaving baskets with interwoven bamboo strips and constructing interwoven circular roofs in Buddhist temples.

Sources:

Pugnale, A., & Sassone, M. (2014). Structural Reciprocity: Critical Overview and Promising Research/Design Issues. Nexus Network Journal, 16(1), 9-35. Retrieved May 16, 2019, from https://link.springer.com/article/10.1007/s00004-014-0174-z

[Portrait of Gauis Iulius Caesar. Marble, augustan age, Roma, Musei Vaticani, Museo Pio Clementino, Galleria dei Busti]. (n.d.). Retrieved May 16, 2019, from https://commons.wikimedia.org/wiki/File:Gaius_Iulius_Caesar_Vatican.jpeg

The image, taken from Wikimedia Commons, is in the public domain.