Sometimes you have a large repository (many commits, many branches) and it either might be an old clone or you might be operating out of a secondary branch and not aware of which branch has the majority of activity. You can do a git-log that displays all commits without respect to the current branch and order them by parents before children, in descending commit-timestamp (as opposed to author-timestamp) order.

This prints the top five:

$ git log -5 --all --date-order