  An important question in biology is how the relative size of different organs
is kept nearly constant during growth of an animal. This property, called
proportionate growth, has received increased attention in recent years. We
discuss our recent work on a simple model where this feature comes out quite
naturally from local rules, without fine tuning any parameter. The patterns
produced are composed of large distinguishable structures with sharp
boundaries, all of which grow at the same rate, keeping their overall shapes
unchanged.
