In a first for science, researchers have created mice that share the traits of the extinct woolly mammoth.
American biotechnology company Colossal Biosciences, which is behind the breakthrough, used a genome editing technique known as CRISPR to create what they’ve called the ‘Colossal Woolly Mouse’.
Rather than miniature mammoths, these are mice whose DNA has been engineered to express mammoth traits. In other words, they look well-adapted for life in a chilly place.
The unpublished research, circulated on pre-print site bioRxiv, explains how the researchers modified seven mouse genes to give them woolly coats – similar in colour, texture and thickness to that of a mammoth.
They say this is the first ‘living model’ of an animal with mammoth-like traits.
“Seeing these mice is a bit like looking back at the past, but with a highly selective telescope,” said Dr Louise Johnson, evolutionary biologist at the University of Reading, who was not involved in the research. “This technology offers an exciting opportunity to test some of our ideas about extinct organisms.”
She added: “The researchers have succeeded in nudging the mouse genome in the direction of a mammoth genome, which is a first.”
So how did they do it? Using complex computer analysis, the Colossal researchers studied mammoth genomes as old as 1.2 million years, as well as those from African elephants. In total, they analysed a total of 121 mammoth and elephant genomes.
They then edited mice genes involved in hair growth and cold tolerance until combining seven of these edited genes produced the desired traits. Crucially, these mice do not contain an exact copy of mammoth genes – and researchers are not even sure these were the same genes that caused those traits in mammoths.
How big a deal is this, really?
Colossal Biosciences says that this development is a milestone in their research on ‘de-extinction’. The company plans on reviving other extinct species with the aim of repopulating ecosystems that are important in balancing Earth’s systems. Its founder, Ben Lamm, has expressed his hopes to bring back the dodo, a giant Ice Age-era bear and an extinct Tasmanian marsupial known as the thylacine.
Not all scientists are convinced that this discovery could have an immediate impact – or that it’s particularly new in the first place.
For starters, manipulating how mouse hair looks has been done before, and genetic engineering has already been used to create ‘humanised’ mice for use in trials on diseases. Scientists have even made mice express traits from the extinct genome of ancient humans.
Nevertheless, several scientists not involved in the research, like Prof Dusko Ilic, professor of stem cell science at King’s College London, have said this “is indeed a noteworthy milestone". The researchers were able to manipulate several genes at once, with unprecedented speed and efficiency.
Also, by comparing mammoth and elephant genomes, the researchers have started to sort through which genes create adaptations for living in cold environments versus the warm places elephants usually live.
Yet Ilic also warns that the next breakthrough – creating a ‘woolly elephant’ – could take years, even decades, given how long it would take to see the results. (Elephant gestation takes two years and then a further 10–14 years until the baby elephant is sexually mature).
This process could also lead to many failed elephant pregnancies and risks to surrogates – an ethical outcome that evolutionary biologist Dr Tori Herridge, of the University of Sheffield, says is “unjustifiable” given it’s an “experiment that – at best – will produce a simulacrum of a woolly mammoth.”
Many scientists, including Herridge, are sceptical that the discovery in mice could translate onto an elephant species with the right characteristics for life in the Arctic.
“A mammoth is much more than just an elephant in a fur coat,” she explained. “While we know a lot about mouse genetics, we know much less about mammoths and elephants.”
She added: “Unless you decide to make every edit necessary to the genome, you are only ever going to create a crude approximation of any extinct creature, based on an incomplete idea of what it should look like. You are never going to ‘bring back’ a mammoth.”
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