Incorporation refers to the free borrowing and modification of cultural elements and occurs when people of different cultures maintain contact as well as political and social self-determination. It may involve syncretism (religious syncretism), a process through which people create a new synthesis of phenomena that differs from either original culture; adoption, in which an entirely new phenomenon is added to a cultural repertoire; and adaptation, in which a new material or technology is applied to an extant phenomenon. Religious beliefs are often incorporated in a syncretic manner, as with synthesis of indigenous and Roman Catholic beliefs in much of Mexico. Technology is often subject to adoption, as with the rapid diffusion of new metalworking techniques and weapon types that marked the transition from the Stone Age to the Bronze Age, and later to the Iron Age in Asia, Africa, and Europe. Ornamentation is often subject to adaptation, as when Native American groups replaced heavy stone pendants with metal ornaments in the period between Columbian contact and military conquest; such ornaments are readily visible in historical portraits of important indigenous personages. Because incorporation is a product of free choice, the changes it engenders are often retained over the long term.