Is there a fifth force of nature?

Locke2005 writes: I've always speculated that there might be forces of nature that we never observed because they were on a much larger or smaller scale than we could detect easily. But now Jonathan Feng, a professor of physics and astronomy at the University of California, Irvine, is suggesting there may actually be a fifth force. Of course, this might vanish just like the Higgs Boson evidence did. Can anybody explain better what it was they detected, and why it is being interpreted as evidence of a previously unknown force?