Nelson Mandela died on December 5th, 2013. People who are interested on this news are also interested on who went to funeral in South Africa and said what. Imagine a news broke in February 20th, 2014 about his visit in Oakland, CA in 1990. If the user lives in or rearby, he/she is most certainly interested on that news as well.
The whole idea is to put a user in a loop about specific news based on the user click/read behavior. That way, a user gets the complete picture of an event.