Marxist or Marxist-influenced archaeologists in the USSR and the UK (among others) often try to prove the truth of dialectical materialism or to highlight the past (and present) role of conflict between interest groups (e.g. male vs. female, elders vs. juniors, workers vs. owners) in generating social change. Some contemporary cultural groups have tried, with varying degrees of success, to use archaeology to prove their historic right to ownership of an area of land. Many schools of archaeology have been patriarchal, assuming that in prehistory men produced most of the food by hunting, and women produced little nutrition by gathering; more recent studies have exposed the inadequacy of many of these theories.