Matthew Carrano of the Smithsonian’s National Museum of Natural History, left, with paleontologist Jack Horner, who wants to use DNA from chickens to recreate a small dinosaur. (Nikki Khan/The Washington Post)
In 2009, the world’s most famous paleontologist made a bold claim. In “How to Build a Dinosaur,” Jack Horner proposed re-creating a small dinosaur by reactivating ancient DNA found in its descendants, chickens. His 2011 TED talk on the subject went viral. And then for the past four years, the public heard nothing.
While the Internet moved on to other viral videos and ideas, Horner and his team have been working on the “chickenosaurus” and moving ahead the science of evolutionary development. The project has already resulted in some of the first research into the embryonic development of tails.
The idea that birds are descended from dinosaurs is no longer questioned within the mainstream scientific community. Paleontologists have long studied the changes in bone structure of dinosaurs and birds over time. Meanwhile, molecular biologists have studied the composition of modern bird genes. By merging these scientists’ work, Horner, who is curator of paleontology at the Museum of the Rockies in Bozeman, Mont., hopes to answer questions about evolution.
Horner’s premise can be viewed from the launchpad of the late Michael Crichton’s novel and film “Jurassic Park,” a story that involved obtaining dinosaur DNA from undigested blood in mosquitoes preserved in amber. The idea of finding dinosaur DNA this way was taken seriously by many people, and the possibility was explored by scientists.
Jack Horner knows the “Jurassic Park” theory very well, having served not only as the inspiration for one of the main characters but also as a technical adviser for the film. But 24 years after the novel was published, we have yet to find any DNA in mosquitoes from the time of the dinosaurs.
Paleontologist Jack Horner thinks some genetic engineering can lead to the creation of what he calls a “chickenosaurus.” (Image by Phil Wilson)
DNA degrades under even ideal storage conditions. Cool, sterile conditions can extend its useful life to as long as perhaps a few million years, and dinosaurs disappeared about 65 million years ago. No matter how perfect a mosquito we find in a blob of amber, we cannot make a dinosaur out of that mosquito’s last blood meal.
There is only one way that DNA has been proved to survive millions of years relatively intact: by replicating itself during that time. This is exactly what happened as birds evolved from dinosaurs.
The obvious choice?
Chickens may not seem like the most obvious modern bird to convert into a dinosaur. Ostriches are the most primitive surviving species of bird. Sandhill cranes have been largely unchanged for about 10 million years. The chicks of a bird called a hoatzin have dinosaur-like claws on their fingertips that they use to climb trees before they are fledged. But ostriches, sandhill cranes and hoatzins would each be challenging to work with in a laboratory. Chickens have the advantage of being highly domesticated and easy to care for at low cost.
Working with chickens also allows scientists to benefit from decades of work that has already been done on their genome and anatomy. A massive amount of research has already been conducted on the domestic chicken due to its economic importance. Poultry science is a large field with long-established journals and entire departments at respected universities.
A genome does not evolve in a tidy fashion. Old genes are not always discarded when they fall out of use. For example, there may be a whole host of genes that direct the growth and movement of a dinosaur’s arm and fingers. If another gene evolved to fuse some of those bones into a wing during embryonic development, many of those arm-and-finger genes would be pushed to the sidelines. But the potential for a dinosaur arm could still be there. If you can identify the newer gene that causes bone fusion and disrupt its expression, those sidelined genes may suddenly start producing arms.
Horner posits that three primary engineering tasks will lead him from a conventional chicken to something resembling a miniature velociraptor (a small predator that became famous in “Jurassic Park”): creation of a long tail; the development of a toothed, beakless head; and the fashioning of arms with fingers and claws instead of wings.
The toothy snout is already here. At his lab at Harvard Medical School, Matthew Harris has made chicken embryos that express ancient genes for the growth of conical, crocodile-like teeth.
