A longing for power and social status mixed with hormones and fear can have deadly consequences. 'Man' via www.shutterstock.com

Men commit over 85% of all homicides, 91% of all same-sex homicides and 97% of all same-sex homicides in which the victim and killer aren’t related to each other.

These startling statistics are driven home with each new mass shooting (though the most recent tragedy in San Bernardino, California is a bit unusual in that a married couple were the shooters).

In any event, politicians and the media are trotting out the usual suspects to explain the tragedy, whether it’s the lack of attention paid to mental illness or the easy availability of guns.

But these explanations dance around the big questions: why is there always a man behind these shootings? And why is it almost always a young man?

Evolutionary psychology can provide some clues.

Precarious Manhood

Psychologists Joseph Vandello and Jennifer Bosson have coined the term “precarious manhood” to describe a dilemma that only men seem to face.

In a nutshell, they argue that “manhood” – however an individual male’s culture might define it – is a status that must be continually earned. And one’s self-worth is tied to being perceived as a “real man.”

It’s precarious because it can be easily lost – especially if the man fails to measure up to the relentless challenges that life throws at him, be they tests of physical bravery, or competition with other men for respect and status.

When I introduce this concept to my male students, they instantly recognize what I’m talking about. But when I ask the women if there’s a female equivalent, I’m often met with confused looks. (Some do note that the inability to have a child could be a threat to womanhood.) Indeed, it quickly becomes clear in the ensuing discussion that “manhood” is more precarious than “womanhood.”