Pixel42
Schrödinger's cat
As this is the Terry Pratchett thread, I assume you're referring to a book by (or partly by) him? The only one I can think of that even vaguely resembles your description isAbout three years ago I think, there was a book called something like, 'what is evolution?'. It was a larger, square-shaped hardback, with many photographs, coloured pages, etc and was aimed at younger people. I thought I was shown a paperback edition of this a few weeks ago in Waterstone's, but when I phoned today, they couldn't recall it.
Does anybody remember it, please?
http://en.wikipedia.org/wiki/Science_of_Discworld_III:_Darwin's_Watch