Realist criminology has two strands: right realism and left realism. Left realism acknowledges the real increase in crime rates since the 1950s and takes crime seriously, especially crimes that affect disadvantaged groups. Left realism advocates a dual approach of practical crime reduction measures and long-term social change to create a more equal society and ultimately eliminate the root causes of crime, which they see as relative deprivation, subcultures formed from blocked opportunities, and marginalization.