How does the dark side of humans play a role in the destruction of society in Lord of the Flies?

I'm assuming your question is more like what role does the
dark side of human nature play in the destruction of society in the novel Lord
of the Flies.  The simplest answer is that it's this darker side of human
nature which leads directly to all the death and destruction in the novel. This is a
highly symbolic work, and it's hard to escape Golding's point that a world without any
external controls (in this case, no adults and no real laws or restrictions) leads to
destruction because the inherent sin or evil in our nature will override any other
elements. 

Each of the boys represents part of who we are. 
Piggy is indicative of our intellectual selves, and when he wants to establish some
order on the island, he is mocked and ridiculed and ignored--and eventually killed. 
Simon represents the conscience or the soul of man, and he speaks the truth (that the
beast is them) but is not heard or believed; instead, he is also
killed.  That leaves Ralph, who is symbolic of our physical selves, and Jack, who
represents our inherent sin/evil/dark nature.  They are the last two elements to
survive, and one is nearly destroyed by the other.  In the end, Ralph is no longer the
leader, he is the hunted.  The dark side of ourselves (represented primarily by Jack) is
the most powerful part of who we are, says
Golding.

Thematically, then, the message is clear--the
strongest element in our beings, according to Golding, is that dark side inside us all;
and without the restraints and controls of a civilized world, that is the dominant
force, though it will inevitably lead to destruction. That's exactly what happens on
this island--until the miraculous and ironic rescue at the end.  It is the dark side of
human nature which destroys this microcosmic world.