 Others pursued more specific analogies notably the anthropologist F. T. (Ted) Cloak who argued in 1975 for the existence of learnt cultural instructions (cultural corpuscles or i-culture) resulting in material artefacts (m-culture) such as wheels.The argument thereby introduced as to whether cultural evolution requires neurological instructions continues to the present day .In the 19th century cultural evolution was thought to follow a unilineal pattern whereby all cultures progressively develop over time.