Last week, the story of the creation of “woolly mice” or “mammoth mice”, was all over our newsfeed.  

Scientists have used gene editing technology to tweak six mouse genes involved in fur texture, length and colour and one gene involved in fat metabolism and absorption – important for staying warm in freezing weather, trumpeted to be the latest step in the “de-extinction” of the woolly mammoth. 

The idea of resurrecting extinct species like mammoths is, for many, an exciting prospect. To bring back an animal that has not existed for thousands of years is the stuff of dreams, sci-fi novels and Hollywood blockbuster franchises, but that’s it. It’s a fiction.

Unfortunately, this doesn’t stop some from having a go, with the backing of wealthy fantasists including Paris Hilton, Peter Jackson and Chris Hemsworth. 

The Mammoth “De-extinction”

The mammoth de-extinction project led by George Church and Ben Lamm aims to resurrect mammoth-like qualities such as woolly coats and other adaptations to cold habitats by switching on mammoth-specific genes in Asian elephants. 

The plan is: 

1. To use DNA from frozen mammoth remains and compare it the genome of Asian elephants.  
2. Identify the mammoth genes responsible for traits like woolly hair and cold tolerance  
3. Modify the DNA of Asian elephant cells using genome editing so that they carry these mammoth genes.  
4. Reprogramme these genetically modified elephant cells to produce stem cells.  
5. Stimulate the stem cells to produce an artificial embryo. 
6. Either implant the embryos in a surrogate elephant mother who will carry them to term, or develop them in an artificial womb, if this becomes scientifically possible. 

Simples? No. Well bits of it might be (relatively). But de-extinction is impossible. Let’s walk through the steps and see what the outcome would mean if it were feasible. 

Comparing Mammoth and Elephant Genomes

The preserved remains of many mammoths have been found over the years, but DNA rapidly fragments and breaks down, making it difficult to get a complete picture of their genetics. Although the first complete genomes of Mammoths were published in 2008, it is only very recently that the complete chromosomal structure of a preserved mammoth has been reassembled, as the 52,000 year old remains were ‘freeze-dried’ very quickly. 

Asian elephants and Mammoths are thought to have had a common ancestor over 2.5 million years ago, when their evolutionary lines diverged. Comparing the genomes of the two species is relatively straightforward and shows their genetic differences, including the genes responsible for the Mammoth’s shaggy appearance and cold tolerance. 

Gene editing Elephant DNA to behave like a Mammoth’s

Genome editing of elephant DNA to introduce Mammoth-like genes into a cell taken from a sample from an elephant may also be straightforward using CRISPR (clustered regularly interspaced short palindromic repeats), a genome editing tool that modifies DNA. 

Subsequently, reprogramming cells to become stem cells is also a feasible, and a similar technique is widely used in biomedical research, including some of the projects Replacing Animal Research funds. 

Creating embryos

In 2024, induced pluripotent stem cells (iPSCs) were derived from samples taken from elephants. Although the scientists reported the formation of embryoid bodies, they had not yet developed elephant embryos from stem cells. 

Embryos can be created from stem cells in a laboratory, using a process called stem cell-based embryo modelling (SCBEM). In humans it is a controversial procedure but it does mean that models of 3D structures that mimic the early stages of human embryo development can be created for human-relevant research purposes.  

Developing mammoth-elephant embryos to full term

If the stem-cell embryo modelling worked here, the result would be a genetically altered (GA) elephant embryo. To then develop this embryo to a full-term baby, would require a surrogate mother. Surrogacy is starting to be used in in vitro fertilisation (IVF) for rhino conservation, but implanting a genetically modified embryo into an elephant carries not just the known risks associated with IVF treatment, but also risks of the unknown biology of the GA elephant. What impacts would the genetic changes have on the baby elephant themselves? How big would they grow? What would their gestation be? Would the baby’s genetic alterations also impact on their mother’s bodies as they grow? 

The alternative would be an artificial womb, which is another area of human research that is still very much in its technological infancy, relying on animal ‘models’ and not without its own human and non-human ethical predicaments. 

So why woolly mice?

It doesn’t take a PhD in evolutionary genetics to know that, for many obvious reasons, doing invasive procedures on multiple generations of elephants is going to be a great deal more challenging than carrying out similar experiments on mice.  

So the team turns to mice to demonstrate a proof-of-principle that the changes found in mammoth genomes can switch on the intended mammoth-like traits that they eventually want to see in their GA elephants. Mice are small, cheap to house, breed quickly, and their genetics has been studied intensely for decades. The authors did not report how many mice they used for this study. 

Even if this was all scientifically possible

Elephants do not do well in captivity. They would have to be used in numerous unnecessary procedures to produce GA elephants. Even if suitable artificial wombs are developed in the future, a fetus of unknown biology, with any potential health and welfare problems that arise due to the genetic alterations, would be brought into a life confined to a laboratory. If multiple animals were to be produced, as is the ultimate intention, then limited genetic diversity of a small population means maintaining a breeding population would be complicated and difficult to ensure continued health and welfare. 

The genetic modification of elephants labelled as the “de-extinction of mammoths”, the absence of discussion around the numbers of animals subjected to procedures, or any benefit that any of this research carries, and the disregard to the animals’ welfare, both during the procedures, and once any ‘resurrected’ animal is born, are all hallmarks of the team’s hubris.  

It is a vanity project disingenuously labelled ‘conservation’. 

Preserving what we still have

While all living elephant species are still on the IUCN red list, and conservation and captive breeding efforts are struggling to ensure their future survival, resources should be channelled into protecting those currently under threat, and the habitats they need, rather than further endangering individuals by using them to create something that they never were. 

If you’re as angry as we are about this, why not let out a good scream into the void? But then it’s time to channel that energy into real change, by donating to support our work you can help create a future where no animal suffers for science.