Before its use to describe biological evolution, the term "evolution" was originally used to refer to any orderly sequence of events with the outcome somehow contained at the start. The first five editions of Darwin's in Origin of Species used the word "evolved", but the word "evolution" was only used in its sixth edition in 1872. By then, Herbert Spencer had developed the concept theory that organisms strive to evolve due to an internal "driving force" (orthogenesis) in 1862. Edward B. Tylor and Lewis H Morgan brought the term "evolution" to anthropology though they tended toward the older pre-Spencerian definition helping to form the concept of unilineal (social) evolution used during the later part of what Trigger calls the Antiquarianism-Imperial Synthesis period (c1770-c1900). The term evolutionism subsequently came to be used for the now discredited theory that evolution contained a deliberate component, rather than the selection of beneficial traits from random variation by differential survival.