What was the significance of the boys' ages? What might these ages represent in society today? What do these ages say about teenagers in general?

Golding most likely chose preteen boys to show a more
rapid decline into savagery.  Older children, or adults even, would be more conditioned
to act a certain way, more inclined to mimic the laws and civilized behavior of their
past.

Golding's children have been taught by their parents,
but they are very immature.  They see the island as fun and games.  Ralph at first does
not take his leadership seriously.  Through the boys' experience on the island, Golding
shows their rapid devolvement into savagery as well as Ralph's painful loss of innocence
and growing maturity.

There are roughly three age groups.
 We have the older ones who are close to the age twelve:  Ralph, Jack, and most likely
Piggy.  We have the middle ones, who are around ten:  the twins, Roger, Robert, and
Simon. And then we have the littleuns, who are  six and
under:

The
smaller boys were known know by the generic title of "littluns."  The decrease in size,
from Ralph down, was gradual; and though there was a dubious region inhabited by Simon
and Robert and Maurice, nevertheless no one had any difficulty in recognizing biguns at
one end and littluns at the
other.

As typical of
neighborhood groups of children, the oldest and the largest becomes the leader.  In this
case, Ralph fits this description.  We are not told Jack's age, but Ralph we do know is
broader than Jack.

Since these characters are not quite
teenagers, I'm not sure if Golding is making a point about teenagers in general, but I
do think he is portraying quite aptly the dynamics of group interaction.  We have the
leader--Ralph.  We have  organizers and confidantes:  Piggy and Simon, and we a
challenger, aggressor, or trouble-maker:  Jack.  In groups we often have those who are
uninvolved or apathetic in the decision-making.  In this case, these are the littluns.
 Golding's characters reflect the roles of most social groups whether it be a school
club, a classroom, a church congregation, or town.

The
various tiers of ages also show the eternal power struggle.  The power struggle between
Jack and Ralph will be echoed in the middle children and later in the younger ones.  In
other words, Jack is not the sole cause of conflict on the island.  Behind Jack is
Roger, waiting for his chance to be the aggressor.  The littluns, it is suggested, will
have a similar dynamic.  In this way, Golding shows us that the enemy is not something
that we can hunt and kill, that it is within us.  The conflicts that the children face
are those that all groups face:  power struggles, apathy, conflicting priorities, lack
of teamwork, and dissension.