Squirrel eating a peanut: photo by Mariappan Jawaharlal, 18 April 2011
Animals simply do NOT "look back", in the human sense, as remorse, regret, nostalgia, etc. They are far too sensible for that. Their demonstration of some semblances of short term memory, e.g. the serial position effect, which privileges recency over anciency, is a strictly practical function. There's a bit of hippocampus activity at work there... but only the tiniest bit. In the related area of spatial memory, the scatter-hoarder creatures are thought to have some ability to relocate their scatter hoards. But this function is limited at best, as anybody who has closely observed the behaviour of squirrels would know. We had a neighbour who for many years sat in his yard feeding peanuts to the squirrels. The squirrels accepted these gifts and immediately busied themselves with burying them. But over the years, the ground became an immense cache of buried peanuts, the location of which had obviously been forgot by the squirrels who had so busily buried them. It was almost funny to watch the little guys bustling about, scrabbling at the ground in one spot after another. It became obvious that their method was to scatter their hoard so generally that, by sheer force of arithmetical chance, sooner or later they could not help but accidentally discover an ancient mouldering peanut. Clearly they had no memory whatsoever of exactly where they had put anything. The same phenomenon occurs in elderly humans.