They are two violent incidents that happened more than 1,000 miles apart, with seemingly little in common other than the senseless bloodshed.

One happened right here in Philadelphia Friday morning, when four gunshots shattered the breakfast-hour calm on Meridian Street in the Holmesburg section. When police finally entered a second-floor bedroom inside the brick twin, they found a longtime, beloved Philadelphia City Council staffer, Linda Rios-Neuby, dead on the floor with three bullet wounds. With the fourth shot, her assailant — her recently estranged husband — had taken his own life.

The other happened last November in a small rural church in a place called Sutherland Springs, Texas. It was packed with Sunday worshippers when a man clad in all black and brandishing an assault-style weapon opened fire on the helpless sanctuary — killing 26 people, including a pregnant woman, a 5-year-old child, and the pastor's teenage daughter, as first responders found many of the dead huddled under pews, some still clutching their Bibles.

But both incidents shared another bond that is far too common in a nation where more than 17,000 people are murdered in a year, at a rate that far exceeds any other developed nation. In each case, the killing was preceded by reports of domestic violence or unrest.

The mass killing in the Texas church by a 26-year-old gunman had followed years of horrific abuse and assaults on women, children and even a dog that didn't stop after the Air Force had court-martialed the man for repeatedly kicking, punching and choking his first wife and even fracturing the skull of his 2-year-old stepson.

Friday's murder-suicide in Philadelphia is still under investigation, but it's already been reported that police had been summoned to the home because of an argument in June — no one was arrested — before Rios-Neuby's disturbed husband returned last week, his twin daughters and their nanny in the home around the time the gunfire erupted.

Philadelphia City Council President Darrell Clarke had tweeted her picture in happier times, nearly five years ago.

News of her death spread shock through City Hall, where Rios-Neuby had risen from an internship to become the City Council's HR director. "Domestic violence is like a pressure cooker of life," Councilman Curtis Jones Jr. told my Inquirer and Daily News colleagues on Friday. "All of a sudden it boils over."

That's the thing: We've heard this sad story line so many times that it almost becomes routine, or at least not a surprise, when, in Jones' words, it "boils over." The underlying problem is that the underlying cause of these killings — toxic masculinity, a poisonous mix of a craving for male supremacy, an inability to properly channel emotions and an inevitable turn toward violence when things are not working out — is so deeply rooted it almost becomes background noise.

That's wrong. The crisis of toxic masculinity needs to be on the front burner of the American conversation — not only because it's so bad, but because it's getting worse.

It's getting worse across the United States, where 50 women are shot and killed by an intimate partner every single month and a number of recent high-profile mass killings — not just Sutherland Springs but the Orlando Pulse nightclub shooting that claimed 49 lives, or the gunman who shot up a congressional softball practice in 2017 and who seriously wounded Rep. Steve Scalise — were preceded by persistent complaints of violence against women.

It's definitely getting worse in Philadelphia, where domestic murders of women such as the killing of Rios-Neuby have spiked by a whopping 50 percent in 2018 — some 21 so far, compared to 14 at this point last year.

The problem has certainly been with us for a long time. Well over a decade ago, a Philadelphia task force found intimate-partner killings comprised a disproportionate share of murders here.

But one thing that has changed more recently is that the internet has encouraged a bizarre strain of toxic masculinity — the so-called "incel" movement of entitled young men whose anger over their failures in attracting women is bonded in chat rooms and, to use that phrase again, "boils over" in occasional acts of horrific violence.

One of them — a murderer who gunned down six people at the University of California-Santa Barbara in 2014 and who, like the others in this column, I won't glorify by naming — filmed a sick manifesto that I'm quoting here because it provides a glimpse into the absolute worst of the toxic male mindset.

"I don't know why you girls aren't attracted to me but I will punish you all for it. It's an injustice, a crime because I don't know what you don't see in me, I'm the perfect guy and yet you throw yourselves at all these obnoxious men instead of me, the supreme gentleman. I will punish all of you for it."

"It's time to have a close look at our culture and what is going on in terms of how masculinity is defined and characterized, which is often as something that is performed or 'proven' through acts of aggression and even violence," Eric Madfis, an associate professor at the criminal justice department at University of Washington-Tacoma, who has researched the links between domestic violence and murder, told Politico earlier this year.

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The points made by Madfis and other experts in a growing body of literature and news reports about "toxic masculinity" are almost always the same. Women tend to internalize stress, depression or failures, while too many men turn instead toward aggression. We live in a culture that both celebrates aggression as a sign of manliness — from the football field to the combat zone to the firing range — and also implies that it's feminine weakness for a man to admit his struggles or seek help. It's telling that the idea that these behaviors are embedded along with the Y chromosome comes through in the way we refer to this as "caveman culture" —  that men are just like this.

A couple of things. Not all men are like this — most men aren't, I'd like to believe, although like any toxin there's always a matter of degree. But the minority of men who are pure poison is big enough that it's sending shock waves through modern American society, and so the other depressing thing about so much of the recent coverage is that while we're numbly familiar with the symptoms, we seem to be at a total loss for any serious cure.

One of those symptoms is the insane availability of firearms in America — a problem with no parallel in other developed nations. It's telling that Second Amendment zealots tend to also reject any talk of toxic masculinity. On the flip side of that, people inclined to say that, look, it's bad human behavior that kills people and not guns are also missing a key point. A nation with no real grip on men's violent tendencies should not be making it so damn easy to go out and buy a weapon. To the contrary, rising toxic masculinity makes common sense gun controls like better background checks and waiting periods a moral imperative. But those things won't make the disease go away.

There is good reason to believe that male violence is less the result of bad genetics and more the result of the backward ways we can continue to socialize our children. Parents can play the biggest role in preaching nonviolence and in teaching boys that it's OK to cry and to reach out for help when things don't work out, as they inevitably do. And America's schools can find innovative ways to teach and encourage a different path for boys. And once we figure out some best practices, governments and philanthropies can support these efforts with dollars — especially since we seem to have so much money to throw away on weapons of destruction.

But the real bottom line is that a problem that starts with men can end with men. I hope other men will join me and the others of our gender who see the realities of unchecked male aggression — and are calling it out. That's a very small first step, but a necessary one. The best way to kill "caveman behavior" is to take it out of the cave and expose it to withering sunlight.