Last month, scientists announced they had extracted RNA from the remains of a thylacine, aka the Tasmanian tiger. The RNA may be tiny, microscopic even, but the ramifications of this extraordinary success are significant for ‘de-extinction’ efforts.
Bringing back species that have disappeared has long been a fascination for scientists – and science fiction writers – but progress has been slow, in part because DNA is only part of the story.
It was almost 40 years ago, in June 1984, that researchers from the University of California at Berkeley announced they had extracted DNA from ‘a scrap of dried muscle tissue’ from the remains of a quagga, an extinct subspecies of the modern zebra.
In the decades since, those vital building blocks of life have been extracted from myriad long-lost species, from mammoths and aurochs to extinction’s ultimate poster child, the dodo –
and even our own relatives, the Denisovans, although no one is suggesting resurrecting ancient humans. However, to truly bring back an extinct animal, DNA is not enough.
DNA, or deoxyribonucleic acid, is the body’s blueprint. DNA in cells contains all the information required to build an entire individual, coded in chromosomes. But to do so, they must specialize and form particular types of cells, a process known as gene expression – and this is where RNA, or ribonucleic acid, comes in.
It is the architect, transforming those plans into a living creature. And now, Dr. Emilio Mármol Sánchez and his colleagues have extracted, sequenced, and analyzed RNA from the 130-year-old remains of a Tasmanian tiger.
The feat is not an easy one, given RNA molecules are much more fragile than DNA, sometimes thought to begin decaying within hours of death.
Now it has been proven possible, that recovered, ancient RNA could supercharge de-extinction efforts. But – and it’s a big but – there are still questions to answer before bringing back a species from the dead, aside from the many other momentous scientific steps required.
Firstly, a philosophical one. If a mammoth was born to a modern elephant, would it know how to behave like a mammoth? Or would it behave like a hairy elephant?
With no other members of their species to learn from, and being born into a very different world from the one they evolved and lived in, any resurrected species are unlikely to be exact replicas of those that preceded them, even if they look the same.
That is not to say they definitely wouldn’t still fulfill the ecological niche they once did, helping shape and potentially restore ecosystems – a key argument for bringing back the mammoth, passenger pigeon and others.
There is the possibility however that the species’ particular niche has already been filled by others in the decades, centuries or millennia since they disappeared. This results in the resurrected species falling in the category of ‘invasive’, despite having technically been there first.