I have the same one you do. My uncles used to sing it all the time when I was a kid. Dreadful song.

"My recurring thought as I watched : is it possible to ensure a greater variety of shapes at the outset?"

Do you mean they should be drastically varied from one another? Or just less less "full"? What would be the advantage? Would this just delay the inevitable or do you think there would be far more varied final shapes?

I think it's even more impressive that this is happening of its own accord. This means they are 1. Intelligent enough to recognize the impending danger and reconcile it and 2. are likely evolving more mental capacity as a result of new dangers (i.e. man). Pretty amazing stuff.