20 Jun Turning Jurassic World into Reality
As Jurassic World conquered the US box office, as it landed the 3rd highest grossing film in 2015, the question of having live dinosaurs in our time has again come to mind. Extracting dinosaur DNA from fossilized amber certainly makes for a great science fiction classic. It’s also called fiction because it’s too far-fetched to happen in real life. Or is it? Modern science has shown promise with a few extinct mammals.
New Life for a 40,000-Year-Old Cave Bear
In 2005, the DNA of an extinct cave bear was sequenced from a tooth and bone. Both samples were over 40,000 years old. Only 6% of the DNA extracted in the experiment proved to be truly from Ursus spelaeus. Contamination by microbes, or even human lab technicians, is a common concern in such studies. The research team compared the results with computer databases to eliminate this error margin. For instance, DNA matching up highly with those of phylogenetically-related species such as dogs were considered genuine. On the other hand, data matching up with microbes was discarded.
A Glimpse of the Tasmanian Tiger
In 2008, scientists injected DNA from the extinct Tasmanian tiger into modern mice. They hoped to get a glimpse of what physiological features certain segments of the Tasmanian tiger genome affected by observing the changes in the mice. The logic was to get a better picture of what the creature looked like while living.
Hope for Mammoths?
Later that same year, a Japanese team led by Teruhiko Wakayama showed that frozen animals could be resurrected. His proof of concept experiment involved cloning dead mice who had been frozen for 16 days. The implication is that perhaps the current collection of frozen mammoth carcasses could someday be used to clone it.
A Tall Order for Dinosaurs
But the aforementioned successes include two luxuries not available to dinosaurs. First of all, the chances of ever discovering a dinosaur preserved whole by ice are extremely unlikely. Secondly, dinosaurs have been extinct for millions of years. The order of magnitude is only a hundred years for the Tasmanian tiger and several thousand for the cave bear. Even dinosaur DNA from soft tissue would be severely degraded.
Turkeys to Theropods?
Perhaps the difficulty of finding quality dinosaur DNA can be completely circumvented by approaching the problem in a new direction. Famed paleontologist Jack Horner believes dinosaurs could be recreated from genetic code provided by their living relatives, birds, and not their dead remains.
The basis for this approach is the hope that birds such as emus and chickens still contain the DNA required to make theropod dinosaurs. If that hypothesis is the case, then chickens should look like velociraptors in the early stages of embryo development.
Hans Larsson, of McGill University in Canada, discovered that a 2-day-old chicken embryo contains a 16-vertebrae reptilian tail before a gene is suppressed and the chicken eventually hatches with a much shorter 5-vertebrae tail. He later discovered that the three-fingered theropod claw is also initially present in the embryo’s wing structure. Matt Harris and Jim Fallon, from the University of Wisconsin, discovered that fangs are present in the chicken’s early development, injected a virus into the embryo to switch on the relevant gene, and hatched a toothed chicken.
These results point towards the blueprint for a velociraptor or Tyrannosaurus rex being preserved in the genome of a chicken. Sean Carroll believes the embryo becomes a chicken because of the “differences in the decision-making that take place during development”. The genes causing the early theropod appearance simply become suppressed over the course of the embryo’s development. In other words, evolution could be reversed by getting those genes to stay expressed.
Jurassic World is Probably Still Not Going to Happen Anytime Soon
Activating or deactivating a certain gene is something today’s geneticists can perform with pinpoint accuracy. So what is everyone waiting for? Completely transforming an emu into what would look exactly like a Mesozoic monster would require fine tuning at least hundreds of traits and a lot of guess-and-check. Larsson was only able to extend the chicken’s tail by 3 vertebrae, despite the full arsenal of modern genetics, and acknowledges that a Jurassic Park scenario could take at least a hundred years.
Furthermore, this elegant strategy would only work for theropods. Sauropods, ankylosaurs, stegosaurs, ceratopsians, pachycephalosaurs, and ornithopods would be too different from birds and therefore out of luck.
Brennan, Zoe. “How Scientists Are Bringing Dinosaurs Back to Life with the Help of the Humble Chicken.” Daily Mail. 13 June 2008.
Palca, Joe. “Scientists Develop Technique To Clone Frozen Mice.” National Public Radio. 4 Nov. 2008.
Wong, Kate. “Cave Bear DNA Sequencing Could Be Boon for Human Evolution Studies.” Scientific American. 3 June 2005.
Young, Emma. “Tasmanian Tiger DNA ‘lives’ Again.” New Scientist. 20 May 2008.