Carl Zimmer in the New York Times:
One factor in the spectacular success of ants is their social life. They live in large colonies in which they divide the labor of finding food, rearing their young and defending their nests. Their societies are so complex that some scientists have studied ants as a way to understand the factors behind our own evolution into a social species.
It’s thus no surprise that many biologists — Dr. Ward among them — have long wondered how ants evolved. In the journal Current Biology, Dr. Ward and colleagues at the University of California, Davis, and the American Museum of Natural History, have now published an evolutionary tree of ants and their closest relatives that may provide the answer.
The authors conclude that the ancestors of ants were wasps. Not just any wasps, though: the closest relatives of ants turn out to include mud dauber wasps, which make pipe-shaped nests on the walls of buildings.