Raising the dead
Two decades after Steven Spielberg’s film first terrified viewers and convinced many that T-Rexes and velociraptors could walk the Earth again, scientists have been able to bring to life embryos of an extinct frog. So are dinosaurs next? Mike Peake repor
He may have looked strangely cute or worryingly toothy – depending on your viewpoint – but the baby velociraptor that was helped out of its shell by a cooing John Hammond in the hit 1993 film Jurassic Park would be 21 if he were around today.
Coming of age in 2014, the movie’s youngest star would now be a pack-hunting, meat-loving, red-blooded adult – assuming, of course, that he’d survived any roaming T-Rexes. And, ahem, that any of this was real.
The initial flurry of extinction-busting possibility that followed Steven Spielberg’s dinosaur blockbuster quickly faded as scientists – as opposed to novelists and screenwriters – rushed to explain that the basis of the movie was actually a load of tosh. Yes, we’d made great strides in our understanding of genetics and of DNA in particular, but no, we weren’t going to be sucking any 150-million-year-old dinosaur blood out of a mosquito preserved in amber any time soon. The world went on its way.
But 21 years in modern science is a long time, and what might have been dismissed as impossible in 1993 is, well, now still nowhere nearer happening – although some scientists are claiming that there might be a different way to do it: by de-evolving birds back into dinosaurs.
All of us carry our evolutionary history deep inside us, which means it is possible – in theory at least – to switch our dormant genes back on. And as the scientific community now accepts that birds are the direct descendents of the rather more large and scary beasts that once roamed the Earth, it doesn’t take too big a leap of faith to imagine a lab team transforming a parrot into something a bit more pterodactyl.
As strange as it sounds, it turns out that this may actually be a much more plausible route to Dino 2.0 than poking around in amber – although researchers have found a minuscule female mosquito that could be at least 46 million years old, fossilised in a piece of shale in Montana, US.
What’s even more interesting: scientists found the last blood meal it had eaten still intact in the insect’s distended belly. Unfortunately, the mosquito was buzzing around in swampy lands long after the mighty animals roamed the Earth so there’s no chance of any of its meal being dino-flavoured. But don’t get disheartened. For starters, let’s begin with… Jurassic Frog.
Actually, calling this resurgent reptile ‘Jurassic’ would be stretching things a little, but the gastric-brooding frog (famous for swallowing its eggs and then giving birth through its mouth) really is extinct, having died out in 1983 after apparently catching a fatal disease that stems from a fungus spread by humans. And that’s what makes the fact that a team of Australian scientists recently succeeded in creating living gastric-brooding frog embryos so remarkable.
The science behind their work is certainly controversial, with critics claiming – just as Jeff Goldblum’s Dr Malcolm character did in Jurassic Park – that extinct species have already had their chance and should not be brought back to life. Undeterred, the professors at the University of Newcastle in New South
Wales – including ‘frog whisperer’ Professor Michael Mahony and cloning specialists Dr Andrew French and Dr Jitong Guo – recovered cell nuclei from frozen tissues of the long-gone frog and implanted them into specially prepared eggs from a different frog species.
After hundreds of attempts, they achieved the impossible and saw the embryos start to grow. Although none of the embryos survived more than a few days, genetic tests confirmed they were full of the genetic material from the extinct species.
The fledgling froggies may have never quite made it to the tadpole stage, but what clearly did have legs was the science itself: the embryos were swimming with brand new, freshly created DNA from the extinct gastric-brooding frog.
“This project and others like it are inspiring others to imagine what was once regarded as unimaginable – that extinction might not, in fact, be forever,” says palaeontologist Professor Mike Archer of the University of New SouthWales, who oversaw the work of the Newcastle scientists. Their work has been dubbed The Lazarus Project – and it has thrown a firework under the possibilities of genetic manipulation and where it might head next.
“We reactivated dead cells into living ones and revived the extinct frog’s genome – an organism’s hereditary information – in the process,” says Archer, whose team’s work was included in Time magazine’s 25 Best Inventions of the Year 2013. “We’re increasingly confident the hurdles ahead are technological and not biological, and that we will succeed.”
And frogs, it seems, are just for starters. By his own admission, Archer’s real ambition lies in bringing something back on a much grander scale. He has his eye on something called a thylacine.
More commonly known as the Tasmanian tiger, the thylacine has roots dating back 25 million years. A dog-like marsupial with a stripy back and a long mouth, it disappeared in the 1930s, having been seen off by dingos and, at the very end, by trigger-happy humans.
For Archer, this tragic furry beast has become something of an obsession because its demise highlights how the colonisation of Australia adversely affected the balance of nature. He wants to bring the thylacine back to life.
“If it’s clear that we exterminated certain species, then we not only have a moral obligation to see what we can do about it, but a moral imperative,” he told a captivated audience last year at the TED De-extinction Conference inWashington. “We’re trying to restore the balance of nature that we have upset.”
After tracking down a pickled thylacine pup – it had been preserved in alcohol for more than 100 years – at the Australian Museum in Sydney, Archer decided to try to extract some of its DNA and see if he could set about ‘de-extincting’ the species.
Initial tests showed, however, that the sample had been heavily contaminated, having been plucked out of its jar for inspection by innumerable curious museum curators over the years. “What we didn’t want to happen was to put this through the machine and have a wizened old curator pop out the other end,” laughs Archer.
Having eventually found betterquality DNA in the pup’s teeth, Archer began to harbour hopes that it could one day be transferred into the egg of a host species, such as a Tasmanian devil, a carnivorous marsupial now found in the wild only in Tasmania.
“Is this a risk?” he asks. “Are we going to get a Frankenstein? No. Because if the only nuclear DNA that goes in is from the thylacine, the only thing that comes out at the other end is thylacine.”
Archer points out that the technique used to bring to life the frog embryos – Somatic-Cell Nuclear Transfer, or SCNT – has also been used to briefly bring the extinct Iberian Ibex (a deer-like mammal with large horns) back from the dead.
“Nuclei from body cells of the last individual animal after it had died were transferred into the egg cells of a goat,” he explains. “And it resulted in a new Iberian Ibex. Although genetically identical, it died shortly after birth following complications with its lungs. That research is starting again, so hopefully there’ll be an even better outcome next time.”
All of which leaves something of a question mark over the whole concept of conservationism. Why save the panda, for example, when scientists could simply knock up a few new ones when we run out? It’s a complaint that Archer hears a lot.
“I think that argument is silly for three reasons,” he asserts. “First, bringing extinct animals back successfully hasn’t been done yet, so take a deep breath. Second, efforts
to do this, whether successful or not, would occur in parallel with modern conservation; it’s not an alternative.”
Finally, he says, the cloning techniques developed to assist de-extinction projects will be useful to enable endangered species to have their numbers increased. Translation: stick rare panda DNA – via SCNT – into the eggs of a non-endangered relative and… bingo!
It’s a fascinating subject – and this is just the tip of the iceberg. For Dr David Penney, a palaeontologist at the UK’s University of Manchester, the real buzz comes from the science’s Jurassic Park implications.
“I was once a kid fascinated by dinosaurs, I have dinosaur models in my office and I would love to see a dinosaur!” he enthuses. “We try to bring back recently extinct species, so really – what’s the difference?”
On a practical level, however, he points out that the amber from which dinosaur blood was extracted in Jurassic Park was actually from a time period well after the dinosaurs’ reign – millions of years later. He also admits that the chance of getting “dino DNA” – as they say in the film – from older amber samples now seems “a highly unlikely proposition”.
Most fossils of insects that have been preserved in amber are unlikely to contain dinosaur blood because the mammoth beasts that once roamed the planet had become extinct by the time the insects were trapped.
Also, many insects decay from the inside out after they’re trapped, leaving little for scientists to try to extract and study. The sample would have to be extremely dry, because DNA can break down quickly if contaminated by water.
Now, suppose scientists did find a preserved mosquito that had gorged on dino blood? It’s an extremely unlikely possibility, but even if it happened scientists would have their work cut out trying to extract any dinosaur DNA because it would be surrounded by the DNA of the host insect. Also, the DNA from other cells in the amber could contaminate the sample, rendering it useless.
The ‘scientists’ in Jurassic Park got around such hurdles by combining dinosaur DNA with frog DNA. But this would be like trying to put together a jigsaw puzzle using billions of pieces that come from two different puzzles, say scientists.
But science charges on, and Dr Penney says that DNA extraction techniques are getting more precise all the time. And if it’s dinosaurs you’re after, maybe you’ve only to open your eyes and look around you…
“Dinosaurs don’t need to be de-extincted,” says Archer, “because there are more of them living on the planet today than humans. Birds are dinosaurs, the only group of dinosaurs that didn’t succumb to the meteoric disaster that wiped the others out 66 million years ago. In fact, most of the classic, carnivorous dinosaurs were actually feathered and would have looked like birds on steroids.”
If that’s not enough, he offers a few final words of solace. “There’s no reason we can’t work back through a living chicken’s genome and return their suppressed dinosaurian teeth, wrist and ankle bones. In fact, that’s already been done in lab experiments.”
Oxford biochemist Dr Alison Woollard, talking to the UK’s Daily Telegraph, adds, “We know birds are direct descendents of dinosaurs, as proven by an unbroken line of fossils that tracks the evolution of the lineage from creatures such as the velociraptor or T-Rex through to the birds flying around today.”
This evolution, she says, suggests that deep within the DNA of today’s birds are the dormant genes that control their long-suppressed dinosaur characteristics.
“In theory, we could use our knowledge of the genetic relationship of birds to dinosaurs to design the genome of a dinosaur,’’ said Dr Woollard.
Like Professor Archer, she too wonders if one day in the near future we will be able to switch the dinosaur genes lying dormant in birds back on.
So if you’re listening, Mr Spielberg, think on. Jurassic Chicken, in which a giant toothy rooster terrorises a suburban shopping mall. We’ll be the first in the cinema queue.