If (numeric variable) increases, do (action)?

(Please keep in mind...I'm more of a code monkey hack than a true programmer. Also, I tried searching and came up with nil.)

Let's say I have variable HUMANS, which is a list of players that's updated whenever EVENT occurs. I have action ACTION that does "stuff".

Basically what I want is this:

If #HUMANS increased when EVENT happened, then ACTION
If #HUMANS decreased, or remained the same, then NIL

Exactly how would one go about that?

[haste]

local HUMANS = 1
function(self, event, newValue)
   if(newValue > HUMANS) then
      -- Do stuff
   end
end