If I called Science's "Breakthrough of the Year" the science world's equivalent of Time Magazine's Person of the Year I'd be exaggerating just a bit. Still, it is noteworthy.
This year, the Breakthrough of the Year is, wait for it, evolution. This might seem strange, since we are approaching the 150th anniversary of the big breakthrough in the field. It really isn't, though. Scientific theories only become static when they are disproven. The initial breakthrough in a subject area is virtually never the final word on things. Darwin provided the initial push, but thousands and thousands of scientists have been working toward a better, clearer, more accurate understanding ever since.
This year, as Science noted, has been a very good one in that respect. The article is, I believe, available for free. Give it a read. It's a good one.