How Old Are Mass Killers?

The latest terrible mass slaughter in Nova Scotia, Canada made me think about the demographic characteristics of mass killers.  Most violent crime, in general, is committed by young or youngish men*, and this seems to have been true for mass killings in the past, too.

But the Nova Scotia butcher was fifty-one.  The Las Vegas killer, in 2017, was sixty-four. 

Mass shootings are statistically fairly rare events.  That makes it hard to see if the two examples I give here are just outliers or if something might actually be changing in the age distribution of mass killers.

Still, this looks to me like a question worth exploring with proper research.**  If there is a change in the age distribution of mass killers, what might be driving it? 

Different weaponry?  Social change now appearing to threaten some in the older age groups?  Different ideologies becoming dominant (Fox News type), some perhaps disseminated by hate online sites and now reaching older age groups than in the past?  Different medicines and supplements older men might be routinely taking now but not in the past?



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* Based on published statistics.

** Or it could all be my imagination.  That is always a possibility.