What do a pigeon and a flamingo have in common? Quite a bit, according to a reordering of the evolutionary tree of birds.
One of a series of studies published Thursday in Science is the latest step toward understanding the origins of the roughly 10,000 bird species that populate our planet.
"We're finally reaching some sort of consensus about how we think birds are related to each other," says Sushma Reddy, a researcher at Loyola University who studies bird evolution and was not involved in the new studies.
Understanding the relationships among different types of birds has been a subject of great debate among scientists because of birds' unusual start.
Birds began as dinosaurs. And for a long time, their ancestors were just hanging around with all the other dinosaurs. That all changed roughly 66 million years ago, when a large asteroid impact triggered a mass extinction on Earth.
Though land-based dinosaurs died, a few bird ancestors survived, explains Edward Braun, a biologist who studies bird evolution at the University of Florida and contributed to the new analysis.
With the big dinos out of the way, the birds spread their wings and covered the entire globe. They quickly evolved to live at sea and on land — everywhere from deserts to the arctic.
"The major groups of birds appeared very rapidly," Braun says.
That's why it so hard to tell who is related to whom. Today's bird species all look and sound very different from each other.
"Owls look very distinctively like other owls," Reddy says. "But there are very few characteristics that would put an owl with any other major group of birds."
The confused family tree has been frustrating researchers like Erich Jarvis, who is an architect of the new studies. Jarvis, a neuroscientist at Duke, has been trying to figure out how different birds learn their songs. To do that, he has to know how the birds are related to each other.
He decided the best way to sort this out was to sequence as many bird genomes as possible. "We just, basically, put out a call and had people come together who were sequencing bird genomes," he says.
More than 200 researchers got involved, sequencing 48 avian genomes. Then they fed that genetic information into supercomputers. The computers crunched the data, and out popped the most likely evolutionary tree for birds. It shows that "only four lineages survived that massive extinction," Jarvis says, "and they gave rise to 95 percent of the species we have on the planet today."
The genetic information reveals other interesting facts about birds, Jarvis says. For example, bird genomes are about a third the size of a mammal genome. Birds appear to have lost a lot of junk DNA, but they also lost some traits to save weight. (For example: They once had teeth but evolved lightweight beaks instead.)
The songbirds Jarvis studies also appear to have independently evolved genes that are similar to those that shape the language areas of the human brain, he says.
The overall tree reveals some surprising relationships among bird species. Parrots are actually close relatives of falcons. Pigeons are more closely related to flamingos than they are to crows. And land fowl, like chickens, are related to ducks.
Julia Clarke, a bird paleontologist at the University of Texas, Austin, thinks the reorganized bird chart that's emerging from all that data crunching is probably correct and is beginning to reveal a clear picture of avian evolution.
"We seem to be sort of converging on a single answer," Clarke says. She's also a bird-watcher and says the genetic studies haven't found their way into bird guides yet.
"A lot of this stuff, I think, should be very compelling to bird-watchers," Clarke says.
AUDIE CORNISH, HOST:
The human fascination with birds can take many forms. NPR's Geoff Brumfiel found that out while reporting on a landmark series of papers about birds that's out today. He asked lead researcher Erich Jarvis to identify this familiar call.
(SOUNDBITE OF BIRD CALL)
ERICH JARVIS: Well, of course, an owl.
GEOFF BRUMFIEL, BYLINE: No, I'm afraid that's a mourning dove.
CORNISH: Jarvis may not know bird calls, but he knows a lot about bird genetics. Here's Geoff explaining how researchers used bird genomes to figure out their evolutionary history.
BRUMFIEL: Birds are actually dinosaurs and for a long time their ancestors were just hanging around with all the other dinosaurs. That all changed about 66 million years ago, says Edward Braun.
EDWARD BRAUN: There was a mass extinction linked to a large asteroid impact.
BRUMFIEL: Braun studies bird evolution at the University of Florida. The land-based dinosaurs died, but a few bird ancestors survived. And with the big dinos out of the way the birds spread their wings and covered the entire globe. They quickly evolved to live at sea, on land, everywhere from deserts to the Arctic.
BRAUN: The major groups of birds appeared very rapidly.
GEOFF BRUMFIEL, BYLINE: That's why it's so hard to tell who's related to whom. Today's bird species all look and sound very different from each other, which brings us back to Erich Jarvis, that guy you heard earlier calling a mourning dove an owl.
JARVIS: We actually study doves in the lab - a ring dove that goes...
(SOUNDBITE OF BIRD CALL)
BRUMFIEL: Jarvis is a neuroscientist at Duke who's trying to figure out how different birds learn their songs. To do that he has to know how the birds are related to each other. He decided the best way to sort this out was to sequence as many bird genomes as possible.
JARVIS: We just basically put out a call and had people come together who were sequencing bird genomes.
BRUMFIEL: More than 200 researchers got involved. They sequenced 48 bird genomes, then they fed the genetic information into supercomputers. The computers crunched the data and out popped the most likely evolutionary tree for all birds. It's published today in the journal Science. What does it show?
JARVIS: Only four lineages survived that massive extinction and they gave rise to 95 percent of the species we have on the planet today.
BRUMFIEL: Those four basic lines have given rise to thousands of bird species and it's surprising who turns out to be related. Parrots are actually close relatives of falcons. Pigeons are more closely related to flamingos than they are to crows. And then there's land fowl like chickens. They're not close to anything except ducks.
Julia Clarke says this new bird reorganization is probably right. She's a bird paleontologist at the University of Texas at Austin and she says data crunching studies like these are starting to show a clear picture of bird evolution.
JULIA CLARKE: We seem to be kind of converging on a single answer.
BRUMFIEL: Clarke is also a birdwatcher, and she says these genetic studies haven't found their way into bird guides yet.
CLARKE: A lot of this stuff really, I think, should be very compelling to birdwatchers.
BRUMFIEL: Remember that parrot-falcon connection? It turns out all songbirds may have evolved from big predators, things that looked like hawks. So maybe those genetic researchers who can't tell an owl from a dove shouldn't feel so bad after all. Geoff Brumfiel, NPR News. Transcript provided by NPR, Copyright NPR.