Lemmings don’t really commit mass suicide. It’s an old myth that was popularized by a staged sea-plunge in a Disney movie in the late 1950s.
To my knowledge, humans are the only animal capable of purposely ending its own life—and certainly the only species capable of mass suicide.
Why is that? What could drive a creature to engage in collective acts of self-destruction?
I suspect that collectivist social activities such as mass suicide, organized warfare, professional sport spectatorship, and Christmas shopping are not part of our genetic heritage, a manifestation of some evolved primate herd mentality. Chimpanzees have been observed engaging in cooperative behavior that includes gang killings and small-scale “warfare;” but there is nothing that would suggest that the participants in these events are not acting independently, as individuals. And we are, after all, 98% chimpanzee. But maybe there is something in that remaining 2% that makes us prone to mindless acts of self-destructive conformity.
Again, to my knowledge, subsistence hunter-gatherer societies have not been observed engaging in mass activities of this sort. They have individual suicide (although at a far lower frequency than occurs in our “civilized” society). And they have warfare. But the warfare is not organized in a way that comes close to comparing with the zombie hoard-soldier approaches seen with agrarian and industrial societies. Modern military combat is predicated on the careful coordination and timing of mass action: an approach reflected in the image of men in identical uniforms marching in lockstep. And our war narratives are laced with tales of selfless bravery: a soldier who jumps on a live grenade to save his comrades; whereas a Plains Indian warrior in battle is a “free agent” who takes orders from his own intuition and experience. He is very unlikely to intentionally take an arrow for a fellow warrior—in some circles, such an act would be an insult to the intended target.
It is difficult to support the idea that mass suicide—or collectivist behavior of any kind beyond that found in the family unit—is part of our DNA. And if the propensity to engage in mass suicide is not genetic, then what is its source?