How to share history between terminal tabs?

I generally find myself using two or three tabs in my Terminal on OS X. A minor inconvenience is that, by default, the tabs don't share their command history. So, searching for a previous command that I ran on another tab by typing history | grep thingIamlooking for does not find it. Is there a way of forcing Terminal tabs to share history, or is there some other "history_of_all_tabs" command?