"Evolution"?

A story on the CNN website is all about how female humans have "evolved" so we can carry the extra weight and bulk associated with pregnancy. This is obviously "evolution" because it's only in humans and their immediate ancestors, not chimps or apes. They went back to the oldest fossils and found the "evolved" vertebra and joint in a 2 million year old female spine. I'm not sure exactly what evidence they are using to call this an evolved characteristic since they don't have any evidence that it was not always there. Except maybe that chimps and apes don't have it, which doesn't really say anything at all. Conveniently, the article wasn't terribly clear on all that.

And they call this science?