How to find out when a contact was added in my iphone?

I know that there are apps that will save the date of newly added contacts, but I was wondering if there's a way to find out when existing contacts were added (such as an activity log).

Good question and the short answer is no. Not that I have come across anyway. It might be a good idea to start thinking about doing making an app to do that yourself especially if you can make money from it. Just done a quick search on Alta vista for you but haven't found anything conclusive sorry.