In the early 1990s, dinosaurs roamed the Earth.
They may have existed only through the magic of Hollywood studios, but the dinosaurs in Jurassic Park alerted a generation to the possibilities and potential pitfalls of editing DNA.
The dinosaurs in the movie were recreated by extracting their genes from blood sucked by prehistoric mosquitoes that had been perfectly preserved in amber.
While science fiction, Jurassic Park’s suggestion that extinct species could be brought back to life became a reality just 10 years after the movie was released.
Cloning the bucardo
In 2003 a mountain goat kid was born in Spain, and lived for just 10 minutes.
Despite its very brief life, this small mammal represented a major scientific breakthrough.
It was a breed of mountain goat known as bucardo, or the Pyrenean ibex, which was once found in northern Spain.
The last ever bucardo, called Celia, died in the year 2000.
However, 10 months before Celia’s death, Spanish conservationists captured her and took cell samples.
These samples were cryogenically frozen to preserve them.
After Celia’s death a team of Spanish and French scientists used a cloning technique adapted from the creation of Dolly the sheep to try to create a clone of her. They took the nuclei from her cells and injected them into goat eggs that had been stripped of their own genetic material.
They then implanted these eggs into hybrids of Spanish ibex and domestic goats.
Despite implanting 57 embryos, just seven of these hybrids became pregnant and six eventually miscarried.
However, one of the pregnancies was a success, and a female bucardo kid was born in July 2003.
Unfortunately, the bucardo clone had a lung defect and couldn’t breathe properly, dying just 10 minutes after it was born.
While the bucardo clone was the first ever extinct species to be brought back to life, it was still a long way from resurrecting dinosaurs.
For starters, the scientists were able to take cells for the bucardo from a living sample.
This simply isn’t possible with dinosaurs, or indeed any extinct species. Living cells have their DNA intact, but after death the DNA degrades over time. This degradation leads to gaps in the genetic information that can be taken from samples of dead species.
In Jurassic Park, the script writers at least acknowledged this problem with ancient dino DNA taken from mosquitoes. In the movie, any gaps in the DNA sequences taken from the blood samples were “filled in” using frog DNA.
There are two big problems with this.
Firstly, it has since been shown that approximately 1.5 million years is the maximum amount of time any readable DNA information can remain intact in well-preserved samples.
With the mass-extinction of the dinosaurs occuring 65 million years ago, the chance of finding any accurate dinosaur genetic information is vanishingly small.
The second problem with Jurassic Park’s “cut and paste” theory was at the time such techniques were notoriously difficult to execute.
However, genetic science has accelerated rapidly since both the movie and the creation of the bucardo clone in 2003.
Cut and paste genetics
While resurrecting dinosaurs remains firmly in the realms of science fiction, Jurassic Park’s prediction of cut and paste genetics was surprisingly accurate.
Around five years ago a technique for easily and accurately editing genetic information emerged from research by scientists in the US.
Known by the acronyms CRISPR/Cas9, the technique has been hailed as one of the most important biological inventions of the 21st century so far.
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats, and Cas9 for CRISPR-Associated Protein 9.
In her TED Talk on CRISPR, molecular biologist Ellen Jorgensen likens Cas9 to a “Pac-man” that wants to chew DNA.
The Cas9 is attached to a genetic sequence called a guide RNA, which matches the piece of DNA that is going to be modified.
Jorgensen describes the guide RNA as a leash keeping the Cas9 out of the genome until it finds the exact spot where it matches the DNA.
Once the guide RNA finds the correct strand of DNA, the Cas9 then cuts it out.
The guide RNA and Cas9 then leave, and a modified strand of DNA is inserted into the gap created by the CRISPR technique.
CRISPR/Cas9 is already being used by scientists to create genetically modified crops and animals.
In China, scientists have used CRISPR to create genetically modified low-fat pigs.
Many believe that CRISPR could be the key to finally bringing extinct species of animals back to life.
‘De-extincting’ the wooly mammoth?
Among the most eye-catching of species proposed for de-extinction is the wooly mammoth.
Unlike dinosaurs, the last wooly mammoths died just 4,000 years ago.
Being based in cold climates, there are sufficient quality samples available for scientists to code the wooly mammoth genome.
And they did just that in 2015, using samples from a 4,300 year old wooly mammoth specimen found off the coast of Alaska, and a 44,800 year-old specimen found in Siberia.
With the genome coded, academics at Harvard are now proposing to splice wooly mammoth DNA into living elephant cells.
They plan to use CRISPR to target strands of the elephant’s DNA related to key woolly mammoth features, such as small ears, subcutaneous fat, long shaggy hair and cold-adapted blood.
In reality, this wouldn’t strictly amount to resurrecting the wooly mammoth.
Instead, it would be a hybrid creature, a “mammophant”, or wooly mammoth 2.0.
Academics who support hybridization of living and extinct species claim that bringing back the characteristics of extinct species could realize many environmental benefits that were lost when they disappeared off the face of the earth.
For example, Harvard genetic professor George Church, who is leading the team developing wooly mammoth 2.0, claims woolly mammoths could help prevent tundra permafrost from melting and releasing huge amounts of greenhouse gas into the atmosphere. They would do this by punching through snow and creating holes that allow cold air to come in.
Similar environmental arguments have been made for the creation of a “supercow” based on the extinct European aurochs. It is claimed the species could help bring back wild meadow areas to the continent, recreating lost ecosystems and habitats for insects and fauna.
Others, such as those backing the re-creation of the passenger pigeon, make the ethical argument that since humans wiped the species out, they have a duty to bring it back to life.
And finally some supporters of de-extinction do so on the grounds of scientific insight.
In Australia, scientists at The Lazarus Project believe that recreating the gastric-brooding frog could offer insights into human digestion.
The frog swallowed its fertilized eggs and turned its stomach into a uterus.
As paleontologist Michael Archer puts it, “I'm not suggesting we want to raise our babies in our stomach, but I am suggesting it's possible we might want to manage gastric secretion in the gut”.
On the tenth anniversary of the birth of the bucardo clone, reports emerged that the scientists behind the experiment had received fresh funding to revive their work. The funding was made on the grounds of protecting the region’s ecology.
Could the trend towards de-extinction and development of techniques such as CRISPR make it third time lucky for this little mountain goat?