From the article:

"This is not an era of good feeling in the United States. We have under our belt eight years of pernicious terrorism angst, six years of Iraq war weariness and, now, months of wondering how bad the American economy's going to get and when — or, worse, whether — it's going to come back. People are tense. There's less inclination to help out your fellow human being."

This fits what we are likely to surmise, intuitively. (Except for the last sentence perhaps.)

At the end, though, it says we haven't been able to figure this out for 40 years or more.

So are there new and different causes, or is this a statistical "cluster?" It matters if an effective response or precaution is being calculated by policymakers.

Christian Science Monitor says that neighbors don't communicate much anymore, and males rarely have social acquaintances outside of the workplace. If you get canned they're likely gone from your life. No one to tell you "hey dude chill for a moment and think about what you just said." (But then you'd have to incorporate marital relationships and trends.)

(Conclusion: None.)