De-extinction: How to Bring Back an Extinct Species

From Jurassic Park to Reality, bringing back extinct species seems fascinating. How is it possible and why should(n’t) we do it?

Author: Patrick Marenda
Editor: Emma Last
Artist: Lucie Gourmet

In 2000, the last living Pyrenean ibex, nicknamed Celia, died crushed by a tree. The species became extinct. In 2003, scientists cloned Celia and, after many attempts, the Pyrenean ibex was reborn. Sadly, Celia 2.0 had difficulties breathing, dying only 10 minutes later. These two deaths make the Pyrenean ibex the only species in the long history of the natural world to have gone extinct twice. 

What are different methods to bring back species from extinction (also known as de-extinction)? 

Doing nothing might work. Certain ecological niches will refill and, through convergent evolution, similar species could reemerge. Another method is breeding and artificial selection. In the Quagga Project, this is done by breeding wild zebras, making them look like quaggas with very few stripes on their back. Both of these methods are not real de-extinction, though, as they only recreate a similar looking animal.

To actually bring back species we need to work with their DNA. For Celia, the method used was cloning: the nucleus of a cell of the extinct species is injected into a cell of a close relative, which will then let the genome of the extinct species express itself. This is a promising technique to save existing species, although it only works if there are refrigerated remains of the species. 

It was thought that cells would survive in the permafrost, making the de-extinction of mammoths easier; however, mammoth DNA is very degraded. So, a project by George Church aims to create a hybrid genome. He started by sequencing the mammoth’s DNA, then replaced the 1% genetic difference between Asian elephants and mammoths by adding the ancient mammoth genes using CRISPR Cas-9 technology. After injection into an elephant cell, this hybrid DNA could birth a hybrid mammoth.

Why do all of this?

First of all, it is certainly exciting to bring back ancient species. But humanity might also want to make an excuse for itself: we caused their extinction but “hey we can bring them back”. Also, proposals have been made to restore ancient ecosystems such as transforming the Siberian taiga back into steppes, which may help fight climate change – mammoths would be some sort of climate activists.

For the non-avian dinosaurs there are again conservation issues. The half-life of DNA is only 521 years, so nothing exploitable survives from 66 million years ago. A paleontologist, Jack Horner found an alternative way: turning chickens into velociraptors by influencing the expression of the genes, especially in the early stages of the embryo. Regrow teeth? Done. Turn the beak into a flatter muzzle? Done. Bring back the tail? Not easy but advancing. Prolongate the legs? Progressing. Although it  would look like a dinosaur, it would remain a chicken with a strange body: again, this isn’t real de-extinction. 

Maybe de-extinction should show more of what it actually does: creating animals transformed by technology, human creations that mirror our relation to nature, instead of resurrecting extinct species.

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