For instance, would you believe that parrots and pigeons are kind of bird-sisters? Did you know that flamingos—which love to splash around—don't seem to be on the same branch of the bird family tree as the rest of the waterbirds?
Hackett and the other scientists were able to figure out all these family relationships by looking at which birds share genes with each other. Birds that share genes share great-great-great-great-great (OK, you get the idea!) grandparents, which means that they should all be on the same branch of the family tree, or at least hanging out on a nearby branch.
It turns out that there are three main groups of birds. There are land birds, like the sparrow you might see hopping around town. There are shore birds, like seagulls that hang out at the beach. And then there are water birds, which include birds like deep-diving penguins. But there are some strange cousins among these groups, birds who have joined the water bird family even though it seems that their evolutionary grandparents were proud members of the land family. -American Association for the Advancement of Science