   # how much you get for free per round
   gain: -> 0
   react: ->
+    start = @hp
     @hp += @gain()
     @hp -= @need()
     @hp = Math.min @hp, @health()
+    @universe.change = true if start != @hp
   # number of times per baby that one can attempt to find it a cradle
   babyTries: -> @genes.babyTries[0]
   # number of health points to transfer to baby

    nextThing()
  remThing: (thing) ->
    thing.dead = true
    for v in ( thing.marges || [] )
      @geoPool.push v
    for k, v of thing.others when v

  moveThing: (thing) ->
    [ vx, vy ] = thing.velocity 
    return unless vx || vy
    @change = true
    thing.x += vx
    thing.y += vy
    if thing.x < 0
