Beautiful photo of happy cats, zuzu. I'm completely sure that cats do have hierarchies - in Cambridge I had some bookshelves built into one of the walls of my house - floor to ceiling; at the time I had six cats. For some weeks after the shelves were installed, the cats occupied one shelf each, with the 'top cat' on the highest shelf and the weediest cat on the bottom shelf, with the others in between in order of rank from high to low.
What I eventually realised was that they were happy with their social order, even if it meant that certain cats got to sit on my lap more than others.
