A 2008 article in "Nature" by Dan Jones stated, "A growing number of psychologists, neuroscientists, and anthropologists have accumulated evidence that understanding many aspects of antisocial behaviour, including violence and murder, requires the study of brains, genes, and evolution, as well as the societies those factors have wrought." Evolutionary psychologists generally argue that violence is not done for its own sake, but is a by-product of goals such as higher status or reproductive success. Some evolutionary psychologists argue that humans have specific mechanisms for specific forms of violence such as against stepchildren (the Cinderella effect). Chimpanzees have violence between groups, which are similar to raids and violence between human groups in nonstate societies, and produce similar death rates. On the other hand, intragroup violence is lower among humans living in small-group societies than among chimpanzees. Humans may have a strong tendency to differ between ingroup and outgroup, which affects altruistic and aggressive behavior. Also, evidence exists that both intragroup and intergroup violence were much more prevalent in the recent past and in tribal societies. This suggests that tendencies to use violence to achieve goals are affected by social mores. Reduced inequalities, more available resources, and reduced blood feuds due to better-functioning justice systems may have contributed to declining intragroup violence.