Preventing cruelty to animals does more than just protect innocent creatures.

It helps us, too.

People get enormous emotional and spiritual benefits from acknowledging the inherent dignity of animals — whether you are watching a hawk pass overhead or comforting an old dog who knows all your secrets and still wants to be your friend.

The wagging tail and adoring brown eyes appeal to our better nature.

At least the vast majority of us feel that way.

But not everyone.

Those who rescue animals and enforce laws against animal abuse see a level of cruelty most people don’t even want to think about. It’s too ugly. Like violence against a spouse or a child, it represents a betrayal of trust at such a fundamental level that it is incomprehensible.

Don’t be outraged because I mentioned animal abuse together with abuse of human beings. I understand the two are not equivalent. But there is a link.

That brings us to a more tangible benefit from efforts to prevent animal cruelty: self-protection.

Since the 1960s, research has shown cruelty to animals to be a gateway drug to violent and murderous actions against other people.

A non-profit in Arizona called the Humane Link (thehumanelink.com) compiled statistics from various researchers. One study found that 70 percent of animal abusers were guilty of at least one other criminal offense and that nearly 40 percent of them had perpetrated violence against people.

Another study found that 48 percent of convicted rapists and 30 percent of convicted child molesters admitted abusing animals when they were young.

A 2003 article in the International Journal of Offender Therapy and Comparative Criminology has the chilling title: “From Animal Cruelty to Serial Murder: Applying the Graduation Hypothesis.” Researchers cite an FBI study in which more than half of 35 imprisoned serial killers said they started by torturing animals.

In many cases, killers were abused or neglected as children. They were passing on the horror they endured, continuing a cycle of violence. It is a cycle that crushes animals and other innocent victims — spouses, children, strangers.

Democratic Rep. Steve Farley says the link between human and animal abuse is one of the reasons he introduced a bill this year to set up an animal-abuser registry in Arizona. Similar to sex-offender registries, it would require those convicted of cruelty to animals, including dog- and cockfighting, to sign up.

Michael Duffey, animal-cruelty investigator for the Humane Society of Southern Arizona and co-chair of the Animal Cruelty Taskforce of Southern Arizona, says such a registry would be a “no-fly list” that animal shelters could use to avoid adopting out any other “potential victims” to convicted animal abusers. Neighbors could be on guard when somebody with a history of dogfighting moved in down the street.

Duffey says intensive efforts to investigate and prosecute “animal cruelists,” coupled with mental-health treatment for animal abusers who need it, will result in a “decline in the number of senseless acts of violence upon our friends and neighbors.” He likes the idea of a registry.

Wayne Pacelle, president of the Humane Society of the United States, doesn’t. “We are not big fans of registries,” he says. “We are really more focused on strong penalties and therefore deterrence.”

The Animal Legal Defense Fund, on the other hand, is a fan. The group committed $10,000 for registry startup costs in Arizona, Farley says. He worked with Maricopa County Sheriff Joe Arpaio’s office on the bill, but it didn’t get a hearing, even though Republican Sen. Al Melvin was a co-sponsor.

“Democratic bills tend to have very high barricades placed in front of them,” Farley says.

But he says lawmakers on both sides of the aisle thought it was a good idea to set up a registry for those who commit “these shameful crimes.” The idea won’t go away. A registry was set up in Suffolk County, N.Y., in 2010, and several states considered bills similar to Farley’s this year.

These discussions show our attitude toward animal cruelty is evolving.

Animals deserve to be protected from violence and mistreatment for their own sake. But crimes committed against them need to be seen as part of larger cycles of violence — cycles that will continue to cause suffering and death until we, as a society, change things.

Reach Valdez at linda.valdez@arizonarepublic.com