The real-life Jurassic Park: Inside plans to bring back dodos, Tasmanian tigers and woolly mammoths

It may sound a little like Jurassic Park — scientists using the DNA of extinct beasts to help bring them back to life.

But although it’s impossible to have Tyrannosaurus Rex walk the Earth again (more on why later), experts say there’s a real possibility that the Tasmanian tiger, woolly mammoth and even the dodo could rise from the dead.

That’s because millions of dollars are being injected into a US startup venture that plans to use a Nobel Prize-winning genome editing method called Crispr-Cas9 to ‘de-extinct’ long-lost species.

First it began working on the mammoth, then the Tasmanian tiger, and this week Colossal Biosciences revealed that its scientists would also be trying to bring back the flightless dodo.

Here, MailOnline looks at how the science works, as well as which other creatures could be revived with the help of either stem cell technology, cloning or a process known as ‘back-breeding’.

Which animals do scientists want to bring back from the dead, and how?

Dodo

Went extinct: 1662 

Lived in: Mauritius

Genome sequenced? Yes, in 2022

Closest living relative: Nicobar pigeon

How could it be brought back? Crispr-Cas9 gene-editing

The dodo is one of the world’s most famous extinct creatures.

But after scientists successfully sequenced its entire genome for the first time last year, efforts are now under way to bring the flightless bird back from the dead. 

Colossal Biosciences, based in Dallas, Texas, wants to ‘de-extinct’ the dodo, more than 350 years after it was wiped out from the island of Mauritius in the 17th century.

Having obtained the 3ft (one metre) tall bird’s genome, experts will next have to gene-edit the cell of a close living relative, which for the dodo is the Nicobar pigeon.

The aim is to make the genome match that of the extinct bird’s, or get as close to it as possible, with the help of Crispr-Cas9.

This is a technique that can ‘cut and paste’ small sections of DNA, meaning scientists can delete or edit certain genes so that they more accurately represent the animal they are looking to recreate.

In mammals, this gene-edited material would then be embedded in the reproductive system of an existing relative of the species.

But because the dodo is a bird, the technique has to be tweaked somewhat because it needs to account for an external egg. This will be tricky, as no one has yet managed to use gene-editing for birds in this way. 

In the dodo’s case, scientists will take primordial germ cells – embryonic precursors of sperm and egg that pass on genetic code from one generation to the next – from a Nicobar pigeon.  

They will then edit these cells to more closely resemble a dodo, such as its flightlessness, and then insert them back into a host pigeon egg.

When the resulting chick hatches it may have a few differences compared to the original species, just because of how challenging it is to 100 per cent replicate an extinct creature’s genetic code.

But it would be a start. 

And the hope is that this dodo-like creature could be born within the next five years.

Woolly mammoth

Went extinct: 10,000 years ago

Lived in: Steppe tundra, from Spain across Eurasia to Canada, and the Arctic to China

Genome sequenced? Yes, in 2008

Closest living relative: Asian elephant

How could it be brought back? Crispr-Cas9

Colossal doesn’t just want to bring back the dodo. 

It is also working to ‘de-extinction’ the woolly mammoth, although it is not the only company that has raised the idea of doing so. 

To do this, in a similar way to the iconic flightless bird, researchers plan to create a sort of elephant-mammoth hybrid using the woolly mammoth’s closest-living relative, the Asian elephant.

Again, the first thing to do is sequence the genome of the woolly mammoth from a well-preserved specimen — such as one recovered after being frozen in permafrost. 

This was first done successfully in 2008.

The next step is where the process differs from the dodo, and birds in general, because it involves using somatic cells such as skin cells, rather than primordial germ cells.

Once again, the DNA from a host living animal – in this case the Asian elephant – is spliced together with that of the woolly mammoth using the CRISPR-Cas9 gene editing tool.    

When scientists are satisfied that the hybrid cells are functioning correctly, the nucleus transfer begins. 

This is where the nucleus from a donated Asian elephant egg is removed, and the hybrid nucleus, which is the Asian elephant nucleus edited with the woolly mammoth DNA, is inserted in its place. 

Electrical pulses are then applied to the egg to stimulate fertilisation, causing it to divide and grow into an embryo. 

After the embryo has developed, it is implanted into a surrogate African elephant, where it will be carried to term.

Colossal hopes the process will end in the birth of a woolly mammoth, or an animal closely resembling the species, which company aims to achieve within four to six years.

Tasmanian tiger

Went extinct: 3,000 years ago

Lived in: Australia and New Guinea

Genome sequenced? Yes, in 2017

Closest living relative: Fat-tailed dunnart

How could it be brought back? Crispr-Cas9

Another venture of Colossal Biosciences, the plan to bring back the Tasmanian tiger was announced in August last year.

This will work in much the same way as with the woolly mammoth.

Once again, skin cells will be taken from a living species with similar DNA – in this case the fat-tailed dunnart – and turned into ‘thylacine’ cells using CRISPR-Cas9 gene editing.

They will then be reprogrammed as stem cells, before new ‘marsupial assisted reproductive technologies’ will be needed to use the cells to make an embryo. 

Once an embryo is created, it would then be transferred into either an artificial womb, or into a dunnart surrogate to gestate.

Christmas rat

Went extinct: Between 1898 and 1908

Lived in: Christmas Island in the Indian Ocean

Genome sequenced? Yes, in 2022

Closest living relative: Norway brown rat

How could it be brought back? Crispr-Cas9

In March last year, scientists revealed plans to bring back the extinct Christmas Island rat, 119 years after it was wiped out. 

This time it is not Colossal Biosciences, but the idea is the same.

An international team of academics outlined in a research paper how the use of CRISPR could lead to the rat’s ‘de-extinction’. 

Rattus macleari, commonly known as the Christmas Island rat or Maclear’s rat, was a large rat endemic to Christmas Island in the Indian Ocean. 

But it was driven to extinction at some point between 1898 and 1908, possibly in 1903, likely due to diseases brought over on European ships. 

The recent study was led by evolutionary geneticist Dr Tom Gilbert at the University of Copenhagen, who said he was planning experiments to ‘de-extinct’ the creature in the near future.

However, he told MailOnline that bringing it back from the dead would not be easy. 

‘The tools are now in theory available that people could use to bring things back… for example, labs are trying use gene editing to change elephant genomes to add mammoth specific mutations,’ Dr Gilbert said.

‘If you were to try use genome editing to change the genome of a living species into a genome of an extinct one, you’d only be able to make some of the changes, not all, so you’d end up with some kind of hybrid. 

‘And that raises the question: what’s the end goal? If you want a hybrid go for it. If you wanted the pure lost form, you’re gonna be disappointed.’ 

In the case of the Christmas rat, the whole process would be the same as for the woolly mammoth and Tasmanian tiger, but would require the rat’s closest living relative.

This is the Norway brown rat (Rattus norvegicus).

Pyrenean ibex

Went extinct: 2000

Lived in: France and Spain, in the Pyrenees

Genome sequenced? No

How could it be brought back? Cloning

Here is where the science starts to differ slightly, and we get more into the realms of the techniques used to create Dolly the Sheep in 1996.

When it comes to the Pyrenean Ibex, it vanished from the Earth a lot more recently than some of the other animals above.

But it also has the unfortunate distinction of going extinct twice.

The first time was in 2000 when the last living Pyrenean ibex, a type of goat, was killed by a falling tree.

Three years later, researchers successfully cloned the creature, only for the newborn to die of a lung defect shortly after birth.

Nevertheless, resurrecting the Pyrenean Ibex focuses on a different method to gene editing.

It involves essentially cloning the dead animal by taking the nucleus from an intact cell, before transferring it into the egg of a close living relative in the hope that an embryo will form. 

The technique is a great de-extinction approach for living species that are close to extinction, because the resulting animal that is created is identical.

But the problem is that cloning requires intact living cells. Therefore it cannot be used on long-lost animals such as the woolly mammoth, Tasmanian tiger or dodo, so CRISPR is needed instead.

Aurochs

Went extinct: 1600

Lived in: Europe, Indian subcontinent and north of Sahara

Genome sequenced? No

How could it be brought back? ‘Back-breeding’

A type of prehistoric cow, aurochs once roamed the plains of Europe but became extinct in the 1600s. 

Despite dying out such a long time ago, auroch genes can still be found in various breeds of cattle in Spain, Portugal and Italy.

This opens up the possibility of a different technique to resurrect the animal. 

Geneticists are now ‘back-breeding’ these descendent species to produce offspring more similar to an auroch.

The only issue is that although the cattle may resemble the auroch, they will never match the animal genetically and will remain two separate species.

Southern gastric-brooding frog

Went extinct: 1983

Lived in: Queensland

Genome sequenced? No

How could it be brought back? Cloning

Scientists are also working to bring back the southern gastric-brooding frog, a species which was native to Queensland but became extinct in 1983. 

They are doing so using a variation of the cloning technique.

This species of frog reproduced in a rather peculiar way – swallowing its fertilised eggs and using its stomach like a womb.

The first step to ‘de-extinction’ the creature took place in 2013 with the transferring of the nucleus from a frozen frog cell into the empty egg of a closely-related amphibian. 

In the same way described above, the cells began to divide and an embryo was created.

However, the experts have so far struggled to get behind this stage as none of the embryos developed into tadpoles or frogs. 

They have been working to overcome the problem ever since. 

Can dinosaurs be brought back to life?

No, sadly (if that’s the right word).

There’s no reason to worry about a real life Jurassic Park in the sense of dinosaurs once again running riot.

In the 1993 film, the prehistoric beasts are resurrected using a DNA-filled mosquito that has been preserved in amber for millions of years.

There is truth to this in the sense that mosquitos from the time of the dinosaurs did preserve in amber.

But when amber preserves things, it tends to preserve the husk, not the soft tissues, which means you don’t get blood preserved inside mosquitos in amber.

It is still possible to find blood residue inside ancient insects, but that doesn’t mean there will be DNA in it, and even if there was, it would be of little use to bringing dinosaurs back from the dead. 

That’s because over time, exposure to UV light and the action of bacteria break down DNA into short fragments. 

The older the sample is, the smaller the fragments are that are left behind, until eventually there isn’t enough left.

So this is why there’s no chance of seeing dinosaurs walk the Earth again.