Whenever I see a little boy throwing rocks at ducks, I wonder whether it was something he learned from another person or is it an instinctual act.  In the animal kingdom most animals will fight for turf, and carnivores will kill for food, but most animals do not commit senseless murder.  However, there are exceptions.  One of the nature shows I watched featured a program on wild mustangs.  It showed a horrible scene where a stallion swiftly and violently killed an injured foal that was not his offspring.  In primates the “common” chimpanzees commit homicide and rape, while their closest (DNA) cousin, Bonobos, are extremely peaceful. 
When I was a kid, I started rescuing animals before I could comprehend what I was doing.  Was it something I just picked up by watching my mom and dad care for our dog and cat?  Was there a “help animal gene” that came through my father (a veterinarian)?  I also liked to hang out with my older brother.  Neither he nor his friends ever exhibited any signs of aggression toward animals—in fact they demonstrated the opposite. 
Research has linked violence and cruelty toward animals with violence toward humans.  In other words someone who abuses an animal is also highly likely to abuse children and abuse their spouse or mate.  Abusers usually had a childhood that included abuse.  When a kid grows up in an abusive home they can go two ways.  They can use that experience to be a catalyst for good, or they can perpetuate abuse.   In order to be a catalyst for good, there needs to be some type of experience where that child feels safe and connected. 
Humane education (where kids are introduced safely to friendly pets and learn about animal care) provides a special gift for abused children.  An animal may be the first real connection that kid makes.  The unconditional love of an animal may just be the catalyst that helps an abused child lean to trust, and then learn to connect, and then learn to live without violence.   It probably won’t be a cure all, but it’s a great start.  For more information you make want to research “the link” and check out Univ. of Washington State, as well as the Humane Association.