Could dinosaurs be brought back to life?

Michael Benton

Palaeontologist Michael Benton ponders the fascinating possibility of resurrecting dinosaurs and how we could go about it 

We see convincing animated dinosaurs in the movies, on wildlife-style documentaries and stadium shows. Surely they can be brought back to life some day? This was the theme of Michael Crichton’s science fiction novel Jurassic Park, published in 1990 and made into the first of a series of movies in 1993. 

Crichton knew his laboratory biology, and he was aware of a remarkable new technology back in 1990, the polymerase chain reaction (PCR), a method to clone DNA, the material of the genetic code. Up to 1990, biologists needed huge samples to read the DNA; with PCR they could take the tiniest sample of hair or saliva and multiply it up for analysis. That’s why nurses or the police need only a small swab sample.

Silesaurus

Back in 1992 and 1993, palaeontologists, the scientists who study fossils, were bowled over by Crichton’s insights. They began running tiny samples of fossil material through PCR and they got positive readings. In one case, the scientists took samples from an insect in amber—just like in the film. Amber is fossilised tree resin and it can trap insects and other creatures on the tree trunks, preserving them in beautiful detail—some amazing specimens from Burma even include wings and other parts of tiny fledgling birds, and even the tail of a heavily feathered pint-sized dinosaur that must have been hunting insects in the trees.

The 100-million-year old insects gave meaningful readings. Then, scientists tried a piece of dinosaur bone, and they got a strange DNA sequence. They compared it to modern crocodiles and birds, and it did not match, so they said this must be a unique dinosaur sequence.

 

Contamination

But they got it wrong. Within a year, another team confirmed that the strange DNA that had been identified as dinosaurian was indeed not from a bird or a crocodile; it was human! The first team hadn’t thought of checking whether their samples were contaminated; a lab technician had sneezed on the slide, and that was enough for PCR to clone up and provide a large enough sample for sequencing!

This was a sober warning. After 1997, scientists who want to study ancient DNA adopt rigours procedures to avoid contamination. The lab technicians have to strip off and wear clean clothing. They never sequence any modern DNA in the ancient DNA lab, they wear masks and gloves, and they don't sneeze. And every night, the lab is cleared of personnel and sealed, and bathed in ultraviolet radiation overnight to kill off any contamination.

With all these precautions, the scientists got a shock. They found that DNA really does not survive well. It is a very unstable molecule after an animal has died and begins to break up within days. They found it was even difficult to sequence the DNA of animals that had become extinct within the last centuries, such as dodos or great auks. Pushing back in time to sequence DNA from ancient Egyptian mummies, thousands of years old, was harder. Woolly mammoths and Neanderthal peoples, who lived side by side maybe 15,000 years ago, have yielded DNA, but it’s very fragmentary, and massive computing power is needed to stitch all the broken fragments of code together. So, there’s no DNA from the times of the dinosaurs, millions of years ago.

 

Cross-species breeding

What about trying another way? There have been many proposals in the news to bring mammoths back to life by extracting mammoth sperm from a frozen male and inseminating a living female Asian elephant, a close relative. So far, this has all been talk, and no action. It sounds plausible, but there are still many technical hurdles—how do you actually find a frozen mammoth in Siberia that it in good enough condition to produce viable sperm? There are rumours that Victorian scientists fed on the meat of a frozen mammoth, but nobody said it tasted any good. Even in ice for thousands of years, the biological tissues break down in certain ways. 

Even if the sperm could be retrieved, the chances that they would fertilise the eggs of an ovulating female Asian elephant are slight—the sperm of course would be dead in the sense they would not swim in the usual way up the females fallopian tubes, so some pretty nifty artificial insemination techniques would be needed. Even so, the alien, and cranky old dead sperm might just not fertilise the eggs.

Experiments have been made to try to bring extinct species back to life. The most famous attempts were made to resurrect the Pyrenean ibex. This was a mountain goat that lived in the Pyrenees between Spain and France, and it was hunted very actively until there were very few left. In fact, the last Pyrenean ibex, a female called Celia, died in 2000, and that was the end of the species. 

However, before Celia died, scientists took fresh DNA samples in 1999, and they attempted to merge these with fresh cells of a goat, a close relative. The ibex-goat mixed tissues began to develop in the laboratory, and they were transferred to a female goat who would act as surrogate mother. Many early attempts failed, but two ibex-goat kids were born in 2009… but they died soon after. The work continues, but so far without success.

 

Bringing dinosaurs back to life

So, it seems the chances of our seeing living dinosaurs in our lifetime are small. The dino DNA does not survive at all, and even in cases where DNA can be retrieved from extinct animals, even some that died out only decades ago, the business of cloning the DNA and especially making a viable embryo is technically very difficult. All the sophisticated laboratory techniques are there, but it just remains tantalisingly impossible to achieve.

We may not see dinosaurs living and breathing. But palaeontologists use a range of smart analytical tools to measure their growth rates, jaw actions, and speed of locomotion. New discoveries show many dinosaurs had feathers, and the colour of those feathers can now be determined, following discoveries in 2010. Find out more about dino DNA, the amazing new fossils from China, and all the methods a new generation of smart young palaeontologists are using to bring dinosaurs back to life in the next best way if we don’t have a time machine.

The Dinosaurs Rediscovered: How a Scientific Revolution is Rewriting History by Michael J Benton (published by Thames & Hudson, April 2019)