What is de-extinction and how do you do it?


Lately there's been a lot of talk about bringing back mammoths from the dead, using a process called de-extinction. How is that possible, and is it a good idea? Stephen Fleischfresser explains.


A woolly mammoth. Will we see it, or something like it, roam the earth again?
Lionello Calvetti

In February of this year, scientists from Harvard University in the US announced their plans to create a live woolly mammoth in just two years.

Wait, what? A woolly mammoth? The massive elephant-like creature with long fur and huge tusks, last seen roaming the frozen tundra in the Ice Age (both the time period and the movie)? Aren’t they extinct?

Well, yes, they are extinct, but that doesn’t seem to matter anymore!

We’ve all heard of extinction. It’s when a species of plant or animal no longer exists, and is normally marked by the death of the last living individual of that species. Extinct species are even famous, like the dodo of Mauritius, or ‘Benjamin’ the last Tasmanian tiger, which died in 1936.

The head of a dodo, published in 'The Dodo and its Kindred', by Hugh Strickland and Alexander Gordon, 1848.
Royal Institution of Great Britain

So what’s ‘de-extinction’ then? Well, if you listen to George Church of Harvard University, it’s the process of bringing an extinct species back to life, and this is exactly what he intends to do with the mammoth!

But how on earth do you do it? Every living organism has tiny molecules that contain instructions on how each organism will look and function. These molecules are called deoxyribonucleic acid, or DNA, and are unique to every living being. Church and his team plan to take DNA from the bodies of mammoths that were trapped in ice or permafrost somewhere between four and 10 thousand years ago, and mix it with the DNA of its nearest living relative, the Asian elephant.

There are many mammoths that have been frozen in the ice in Siberia that modern scientists have preserved in laboratories. Scientists can extract the DNA from the these to de-extinct the species! The problem is that after an organism dies its DNA tends to break up and degrade.

DNA has a half-life of 521 years, which means that if we take a strand of DNA now and wait 521 years (bit boring, I agree) only half of the DNA will still be intact at the end of that time. The last living mammoth died roughly 4000 years ago and many of the specimens scientists have are much older than that, so, although we have whole bodies of mammoths, we don’t have whole copies of their DNA. So how do you fix that? Here comes the Asian elephant to the rescue!

By using the DNA of the elephant, scientists can patch up the holes in the mammoth DNA to produce a whole DNA sequence that can be used to create a live mammoth. The Harvard team are using the new and incredibly exciting gene-editing technology called CRISPR to do this. CRISPR is short for ‘Clustered regularly interspaced short palindromic repeats’ (now we know why they just call it CRISPR!), and is the most precise, easiest and least expensive way to take genes and put them wherever you like.

Genes are short sections of DNA that are responsible for particular characteristics of an organism, such as hair colour or ear size. This amazing technology will enable scientists to take the mammoth genes and insert them into the DNA of Asian elephants to produce a complete sequence. After that, the DNA will be placed inside an egg cell of an Asian elephant, and from this will grow a live mammoth.

Church and his team believe they can do this by 2019, just two short years away. Not long after that, we hope, there will be mammoths wandering around all over the place! But, hold on! If you’re mixing mammoth and elephant DNA together, do you really get a woolly mammoth?

A 1961 reproduction by Henri Breuil of an auroch, painted in a Spanish cave between 14,000 and 34,000 years ago
Paul D Stewart/Science Photo Library

Well, sort of. What you really get is a ‘mammophant’, a hybrid of a mammoth and an elephant. It would totally look like a mammoth though, with long tusks, small ears and long shaggy fur. It would even have some other mammoth traits, such as blood that is adapted to very cold weather. So, although it might not be exactly like the woolly mammoths of the past, it will be pretty close, and half a mammoth is better than no mammoth at all, right?

So if scientists can de-extinct a mammoth, what other extinct species might be brought back to life? Around the world, researchers have already begun work on de-extincting the dodo, the auroch (a super-huge ancestor of the modern cow), a long-lost species of zebra, cave lions and lots more. Mike Archer of the University of New South Wales and some colleagues are seriously investigating the possibility of resurrecting the Tasmanian tiger (or thylacine as it is properly called).

So perhaps we can de-extinct species that have died out, but should we? Should we bring back the mammoth? It’s a tricky question. Mammoths, like elephants, were a social species: they need the company of other members of their own species. If we only bring one individual back to life, won’t they get terribly lonely? Well, perhaps over time scientists can create a large number of mammoths so they can have friends to socialise with. But then we’d have a huge herd of big, powerful, hungry mammoths. Where will they live?

There actually might be an answer to that. There is already a place called Pleistocene Park in north-eastern Siberia where scientists have recreated much of the environment of the last Ice Age. This is exactly the environment which mammoths lived in 10 thousand years ago. So it is here that scientists are thinking of releasing mammoths into the wild.

So maybe we can de-extinct mammoths and thylacines, but the big question is: can we de-extinct a dinosaur? Can we finally make Jurassic Park a reality? Unfortunately, the answer seems to be ‘no’. Where the mammoth has been extinct for 4000 years and the thylacine for less than 100 years, the dinosaurs have been extinct for 65.5 million years. Given the half-life of DNA is 521 years, it is nearly impossible that enough genetic material would remain intact for us to be able to use to de-extinct a dinosaur.

Sadly, Jurassic Park must remain on our movie screens for now. Instead, we will have to make do with Pleistocene Park. It might not have a T-rex, but it could have mammoths – and that’s pretty awesome.

Stephen fleischfresser.jpg?ixlib=rails 2.1
Stephen Fleischfresser is a lecturer at the University of Melbourne's Trinity College and holds a PhD in the History and Philosophy of Science.
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