Jurassic spark: Is there a future in dinosaur cloning?
In the 20 years since Steven Spielberg's benchmark-setting blockbuster was released, advances in science have debunked some of the assumptions made by the filmmakers. And, while it may still be possible, palaeontologist David Hone makes no bones about the future of dinosaur cloning
Even at nine in the morning, the temperature in the Gobi Desert in August can be unpleasant, although oddly the lack of humidity makes it more tolerable than Beijing, 2,400 kilometres to the east. In the morning light, when the shadows are longer, small things sticking out of the rock are easier to spot and, as I move closer, a fragment that caught my eye becomes unmistakable – it is a piece of fossil bone. This is the first decent thing I’ve seen in days – the rocks of the Junggar Basin in Xinjiang Uygur autonomous region yield spectacular fossils of dinosaurs, often complete skeletons of new species, but these are rare and hard to find.
Excited, I clear the sand away. After only a few minutes, I can see it is more than a fragment: it is nearly a whole bone, probably a part of a hand or foot. A few more minutes’ digging and it is clear there is more than one bone here. I shout at two members of my 15-strong team to come and help. By the afternoon there are five of us working at the site, by the next day, seven, and a couple of days later we have excavated a block of stone that is so heavy it requires almost the entire Chinese- American crew (plus one token Brit – me) to haul it out of the valley and into a 4x4. We’ve shifted hundreds of kilograms of rock, mostly by hand, under a punishing desert sun. But it has been worth it. By the end, we have removed perhaps half the skeleton of a carnivorous dinosaur.
THESE ARE THE MOMENTS palaeontologists like me live for. Such a find can radically enhance our understanding of what dinosaurs looked like and how they behaved. And, such game-changing discoveries aside, smaller research projects are constantly revising what we know about these extraordinary animals. Fifty new species are discovered on average each year.
The general public’s idea of a dinosaur is far less fluid. Today, most people’s perceptions are based on one film: Jurassic Park. At the time of its release, in 1993, the Steven Spielberg movie was a landmark in special effects thanks to its remarkably realistic computer-generated dinosaurs. It was a classic Spielbergian romp, charting the story of a theme park on an island off the coast of Costa Rica that plays host to dinosaurs brought back from extinction by a team of genetic scientists.
Inevitably the animals are let loose and create havoc, making a literal meal of the guests on the island, who are there to assess the safety of the park for the public. The film reignited interest in dinosaurs and sparked copycat films, documentaries and even research (one palaeontologist entertainingly estimated the number of lawyers it would take to feed a Tyrannosaurus rex for a year).
And, it has to be said, palaeontologists at the time were largely delighted with the film.
“Most people in palaeontology grew up watching movies with jerky stop-motion dinosaurs or lizards with horns glued on,” says Tom Holtz, a senior lecturer at the University of Maryland, in the United States, who had just completed his PhD when the film was released. “So when Jurassic Park came out, here for the first time on the big screen were the dinosaurs we knew as professionals.”
The appearance of the dinosaurs on the screen was superbly rendered, for the time – they moved gracefully, yet with real weight, and also breathed, blinked and generally looked far more like living animals than almost any had previously.
But that was 20 years ago (to celebrate the anniversary, Universal Pictures has just re-released the film in 3D) and palaeontology has come on leaps and bounds in the intervening period. As a result, Jurassic Park looks increasingly like a relic from a bygone age, much like its subject matter. And one of the dinosaurs whose depiction is now questioned is the legendary Tyrannosaurus rex.
Just over a decade ago, a Chinese researcher sent shock waves through the palaeontology community when he brought what many considered close to a holy grail to a conference in the US: a fossil dinosaur with feathers. Since then, scores more fossil specimens have been unearthed in China, Germany and Canada showing that many dinosaurs of the lineage called theropods (containing all of the carnivorous dinosaurs) had feathers of one kind or another. In fact, some were so completely covered in large feathers they would have looked rather like toothy ostriches, or even chickens. So, far from boasting a brown-green scaly hide, it’s now thought the fearsome Tyrannosaurus rex might well have been fluffy.
Research has also revised the reputation of another of Spielberg’s stars: the velociraptor. In Jurassic Park, the “raptors” – as they are known in the film – are the size of a human and portrayed as highly intelligent pack hunters. The idea of pack hunting for this genus and its near relatives was popular in scientific circles at the time, so Michael Crichton, on whose book the film was based, can be forgiven for portraying them this way. But the evidence has been shown to be limited.
Fossils of multiple deinonychus (a creature similar to the velociraptor) have been found in proximity to each other, but there’s no reason to think that just because they are preserved together they habitually lived together. “Raptors” were also half the size of their screen counterparts and, while their brain size marks them out as probably smarter than the average saurian, they were not among the smartest of their kin, and would probably not have seriously challenged the apes or the more intelligent birds.
The colours and patterns of the dinosaurs in Jurassic Park are also questionable. The truth is, there is much we don’t know about these beasts – after all, it’s thought only one in every million dinosaurs ended up as a fossil – and the colour of their hides (or plumages, if they had feathers) is one such “black hole”. Some tentative steps have been taken: tiny particles called melanosomes are preserved in fossil feathers and their shape is directly linked to the pigments they contained. We now know, for example, that a dinosaur called a microraptor, which glided from tree to tree using two pairs of wings, was a similar colour to a modern crow. But there is much research to be done.
We also have very little idea what they sounded like. Jurassic Park is full of roars, clicks and screams, but these are all figments of the filmmakers’ imagination. They may be accurate; they may be wrong. Again, some small advances have been made in recent years. The first studies on the structure of the inner ears of dinosaurs give us some idea of the range of sounds they might have been able to hear (and therefore the range of sounds other dinosaurs made), but we have a long way to go.
And what of the genetics at the heart of Jurassic Park? When the film came out, almost as many column inches were filled with speculation about the feasibility of Crichton’s science as were taken up with reviews. Palaeontologist Jack Horner, Spielberg’s chief technical adviser and the inspiration for Sam Neill’s character in the film, went on record declaring, “Of course we can bring dinosaurs back to life. Their ancestral DNA is still present. The science is there.” Most experts, however, dismissed this as studio hype. But, like palaeontology, the science of cloning has made gargantuan strides in recent years. Dolly the sheep, for example, was still several years away when the film was released. So is the concept of reviving extinct species still regarded as far-fetched?
Crichton’s beasts were resurrected using dinosaur DNA recovered from the bellies of bloodsucking mosquitoes trapped in amber. The genetic information was incomplete and so was filled in with bits of DNA from other animals to make up for the loss. No scientists today are doing anything like this, of course, but they are trying to resurrect a creature that died out almost 10,000 years ago: the woolly mammoth.
A team from the Siberian Mammoth Museum and Japan’s Kinki University announced in December 2011 that bone marrow cells of a mammoth unearthed in the Siberian tundra were remarkably well preserved and ideal for cloning.
The scientists planned to extract a nucleus from a cell and insert it into the egg of an African elephant as part of an experiment that they expected to take at least five years. At the time of the report, Charles Foster, a fellow at Green Templeton College, Oxford University, in Britain, told the BBC: “The idea of mammoth cloning isn’t completely ridiculous.” And Ian Wilmut, the embryologist who led the team that cloned Dolly the sheep, has not completely dismissed the idea, either.
But resurrecting a dinosaur depends on the less-than-trifling matter of getting hold of dinosaur DNA. New discoveries are constantly extending the length of time we know that DNA can survive. Recently, genetic data from a horse that lived more than 700,000 years ago has been described.
However, the last dinosaurs died out more than 65 million years ago. To say there is a long way to go is something of an understatement.
Even if a complete DNA sequence were discovered, there is another problem: for cloning to take place, the DNA needs to be put into a compatible living cell. And once that cell has divided a few times to become a viable embryo, it needs to be transplanted into a surrogate mother.
In the case of the mammoth DNA, scientists want to use an elephant, but that raises ethical questions because elephants are an endangered species. As Wilmut points out, the researchers will need to use “hundreds of eggs”, interfering with the elephant’s reproductive output.
Other scientists question the idea of reviving long extinct species under any circumstances.
“It is unethical because these animals belong in the past,” says Scott Elias, professor of quaternary science (study of the quaternary period – the past 2.6 million years on Earth) at the University of London. “Their ecosystem doesn’t exist anymore, and any animals that were created would have to be confined in a zoo and limited to an artificial diet.”
Some scientists propose another way of resurrecting dinosaurs.
Birds, they point out, are descended from theropod dinosaurs, and carry inactive genes closely related to genes in dinosaurs. We have already produced chickens that grow teeth – the genetic mechanism for teeth is still there, so by switching this back on during development, a chick is born that will grow them. Might it be possible to “flip some switches” and produce a bird with dinosaurian features?
But, there are, in my opinion, better ways to apply our knowledge of the prehistoric world. Palaeontology, for example, tells us important things about the extinction of species. Gathering data from over millions of years helps us to identify patterns and trends that allow us to better understand life on Earth. Some discoveries have even informed modernday engineering projects. Research I have been involved in on the structure of the wings of the pterosaurs was studied by a company working on biomimetic membranes; material that has been applied, in other projects, to the design of fighter jets. With the rates of discovery in both palaeontology and genetics continuing apace, who knows what could be achieved over the next 20 years? But I for one am not yet worried about the dangers of marauding tyrannosaurs.