"More than two decades of psychological and sociological research reveals that barbarous acts toward animals often lead to brutality toward humans. Such violence has been observed in serial killers, who often began their sprees of violence by practicing on animals, but is well-documented in cases of domestic violence and child abuse as well."
www.nhes.org
www.nhes.org
Behavioral/Psychotic Disturbances
"Many psychological theories have attempted to explain the possible causes of troubling human behavior that lead to animal cruelty/torture and violence against other humans. Often, considerations are made for extreme emotional and psychological traumas; and in recent decades, emphasis has been placed on studying disturbances to biological brain functions and development. Emerging information suggests that underdeveloped and/or improperly functioning parts of the brain related to behaviors, such as impulse control and specific emotions such as empathy and anger, may be the cause of some violent behaviors."