the nature of nostalgia

I’ve been continuing to read about the self, and had a puzzle solved for me today. I’ve heard a number of times that one thing that makes us different from other animals is that we can project ourselves into the past and future, whereas other animals can’t. What’s been bugging me is that lots of animals have memory, so how is it exactly that our conception of the past differs from other animals? The paper (written by a colleague in my department) argued that what we can do and others can’t is that we can imagine what it was like to be in a different mental state to the current one. So, the idea is that if an animal is hungry, it can’t remember what it’s like not to be hungry.

This may sound kind of weird, but research with kids suggests that humans are like this too up until around 3 or 4 years old. For example, if you teach a child under 3 something new they’ll typically tell you they’ve always known what they were just taught (I think they way they test this is to ask them the day after they’ve learned the new thing). So they think the way they are now is the way they’ve always been.

This all suggests that an important part of our identity is recognizing how we’ve changed over time. I suppose the interesting question is, with all that change, how we hold on to a stable sense of a core self that is unchanged from childhood to now.