Evolution in reverse: Could this chicken become a dinosaur?
Credit: sanddebeautheil, Shutterstock
Paleontologist Jack Horner has always been a bit of an iconoclast. In the 1970s, Horner, the curator of paleontology at the Museum of the Rockies in Bozeman, Mont., and his friend Bob Makela discovered a Maiasaura nesting site, painting the first picture of dinosaurs as doting moms and dads. He's also been at the forefront of research suggesting that dinosaurs were fast growing and warm-blooded.
But Horner's newest idea takes iconoclasm to a new level. He wants, in short, to hatch a dinosaur.
Or something very much like one, at least. Horner, who served as a technical advisor for the "Jurassic Park" movies, has no illusions that the technique in that movie — extracting dino DNA from mosquitoes in amber — would work. DNA degrades too quickly, for one thing. Dinosaur DNA has proved impossible to extract from actual dinosaur bones, never mind blood-sucking insects.
"If you actually had a piece of amber and it had an insect in it, and you drilled into it, and you got something out of that insect and you cloned it, and you did it over and over and over again, you'd have a room full of mosquitoes," Horner said in a February 2011 TED Talk in Long Beach, Calif. TED, or Technology, Entertainment and Design, is a nonprofit focusing on "ideas worth spreading."
So Horner has another idea: Use the living dinosaurs among us to recreate creatures dead for millions of years. Anyone who's seen "Jurassic Park" knows that birds are dinosaurs, part of the evolutionary line containing those toothy Velociraptors. What's less known is that organisms carry their evolutionary history with them. Human embryos, for example, have temporary tails, which are absorbed by the body during development. Rarely, babies are born with vestigial tails, the result of scrambled genetic processes that prevent the tail from getting re-absorbed. These evolutionary remnants are called atavisms.
Enough atavisms have been discovered in birds to make the idea of "reverse-engineering" a dinosaur out of, say, a chicken possible, Horner says. You wouldn't be adding anything to the bird to make it more dinosaurlike; all the ingredients are in its DNA. Horner's goal is to figure out how to wake up those ingredients.
LiveScience talked with Horner about his "chickenosaurus" plan and what sort of dinosaur he'd like to keep as a pet. [Infographic: How to Make a Dino-Chicken]
LiveScience: What was the genesis of this chickenosaurus idea?
Horner: Knowing that birds descended from dinosaurs and knowing the changes that occur from dinosaurs to birds, we know that the changes that did occur occurred because of genetics.
A friend of mine, Hans Larsson at McGill University, was studying some of these changes and looking into how it was that dinosaurs lost their tails in the transformation from dinosaurs to birds. They also transformed their arms from a hand and an arm to a wing. I got to thinking, if he discovered the genes that were responsible for both of those transformations, we could just simply reverse evolution and reactivate the tail, and possibly make a hand back out of the wing.
And then what we would have by doing those two things, you'd actually take a bird and turn it into an animal that looked a lot like one of the meat-eating dinosaurs. It seemed like a good idea.
LiveScience: What kind of animal would chickenosaurus be?
Horner: It's still a chicken. It's a modified chicken. You'd really have to mess with the DNA to make it something different.
The most important thing is that you cannot activate an ancestral characteristic unless the animal has ancestors. So if we can do this, it definitely shows that evolution works.
LiveScience: You've mentioned in the past that you see this dino-chicken as a teaching tool to help people understand evolution. Do you see that working?
Horner: Of course. You bet. There are people who are misinformed, and there are people who are uninformed [about the validity of evolution]. If people are uninformed, this will probably get through to them. If they've been misinformed and don't mind being misinformed, then they probably will continue to be misinformed.
LiveScience: Either way, it'd be a pretty awesome thing to take into a classroom.
Horner: Yes, it would. Exactly.
LiveScience: Starting with a chicken, how close could we really get to what a dinosaur looked like?
Horner: We're working with an animal that has all the right stuff. It's more about subtle changes, adding a tail or fixing a hand or possibly adding teeth, what we would think of as being relatively simple changes rather than messing with physiology or something like that.
A bird is really a dinosaur, so we're pretty sure that the breathing apparatus of a bird evolved from the breathing apparatus of a dinosaur, and is therefore completely different than a mammal. The physiology of a bird is evolved from a dinosaur and not from a mammal, so it's not like we're trying to take a mammal and turn it into a dinosaur.
LiveScience: Would chickenosaurus teach us anything about dinosaurs we can't learn from fossils?
Horner: It's not really about understanding dinosaurs at all. Once we learn what certain genes do and how to turn them on and turn them off, then we have great potential of solving some medical mysteries. There are a lot of ways to think about this, but it's not really about dinosaurs other than solving Hans Larsson's problem of figuring out how birds lost their tails. [Tales of 10 Vestigial Limbs]
LiveScience: What do you see as the biggest challenge of making chickenosaurus happen?
Horner: The biggest challenge, first off, is to find the genes. We know that in the development of a tail, there are a variety of things that have to happen, so there are a couple of ways to possibly go about this.
One, as we know, when a chicken embryo is developing in the egg, just like basically all animals, the embryo actually for a time has a tail and then the trail re-absorbs. So if we could find the gene that re-absorbs the tail and not allow that gene to turn on then we could potentially hatch a chicken with a tail.
The other method would be simply to go in and discover what Hox genes [the genes that determine the structure of an organism] might be responsible for actually adding tail vertebrae, and then to see if we could add some, either by manipulating the Hox genes or by using temperature. There have been some experiments done showing that adding heat will add a vertebra here or there.
LiveScience: Where are you in this process now?
Horner: Right now, mostly I'm looking for a postdoctoral researcher. An adventurous postdoc who knows a lot about developmental biology and a little bit about birds and has done some work about chickens to work in our lab here in Bozeman.
Me, I just go through the literature, looking for anything that might give me a clue as to what genes might be responsible for tail absorption or tail growth or something that might help me with hands.
LiveScience: The comparisons to "Jurassic Park" are easy to make, but have you ever seen the movie "The Birds?" Do we really want chickens with extra teeth and claws running around?
Horner: You can't really compare it to either movie. First off, you can go out in the Serengeti and there are all kinds of animals that will eat you, but if you're driving around in your Jeep, you're just fine. The lions and cheetahs and leopards are not going to try to get into your Jeep when there are plenty of plant-eaters out there to eat that aren't inside of a metal cage.
That's the funny thing about "Jurassic Park," right? All these dinosaurs want to eat people no matter how hard they are to get.
So we don't have to worry about "Jurassic Park," because that's just fiction. Animals don't act that way. They're not vengeful. And birds aren't vengeful either.
LiveScience: So if you could bring a dinosaur back — the real thing, not a modified chicken — what species would you choose?
Horner: A little one. A little plant-eater.
LiveScience: No T. rex for you?
Horner: Would you make something that would turn around and eat you? Sixth-graders would do that, but I'd just as soon make something that wouldn't eat me. And you could have it as a pet without worrying about it eating the rest of your pets.