The line between broken and useful traits can be hazy in biology, leaving open the possibility that what is now considered a malfunction might once have been promoted by natural selection.

We might find it tricky to think of evolution benefiting antisocial people, but nature has no problem leaving room for the occasional freeloader within otherwise cooperative species like our own. Those alternative traits that make psychopaths so despised could feasibly give them an edge in a world where competition for resources is intense.

A team of Canadian researchers explored this possibility in a study published last year in the journal Evolutionary Psychology, arguing psychopathy lacks certain hallmarks of a disorder, so should be considered more like a function operating as intended.