The concept of breathing life back into creatures long vanished from our planet has evolved from science fiction to a tantalising reality. A host of extinct species that once roamed the four corners of the Earth are no longer confined to history books, given the immense development in scientific exploration and biotechnology. This new frontier has challenged our ideas of extinction and blurred the lines between past and present.
The 1993 cinematic epic Jurassic Park depicted the cloning of dinosaurs, and they being brought back to life after their DNA was found intact within the bellies of prehistoric mosquitoes preserved in amber. While it is established that going back 65 million years to find intact DNA traces is far-fetched, scientists have bet on more later extinct species.
While the science of cloning is still in its infancy, many scientists believe it’s only a matter of time before extinct animals walk the Earth again. Woolly mammoths, passenger pigeons, Tasmanian tigers, aurochs, quaggas, dodos, and a host of other extinct animals could make a comeback, through a process called “de-extinction”. To simplify, de-extinction, or resurrection biology, reverses plant and animal extinctions by creating new versions of previously lost species through several methods.
The ultimate goal is to reestablish dynamic processes that produce healthy ecosystems and restore biodiversity, explains Colossal Biosciences, the company behind the efforts to revive the dodo – an extinct bird native to Mauritius – and now the mammoth. This can be achieved through bioengineering techniques that can manipulate DNA and genomes or the genetic material in an organism. Recovered DNA, whether from the Pleistocene or the twentieth century, can make ancient creatures come to life, scientists strongly believe. Some techniques for species restoration are back-breeding, cloning, and genome editing.
Back-breeding is a form of selective breeding that involves breeding animals for ancestral characteristics. Though this technique has its limitations, it can recreate some traits of an extinct species, but the genome will differ from the original species. Similarly, cloning is a well-accepted method for de-extinction. It can be done by extracting the nucleus from a cell, which is preserved from the extinct species and swapping it into an egg, of the nearest living relative.
A popular example is Dolly, a female sheep and the first mammal that was cloned in 1996 from an adult somatic cell by Roslin Institute, University of Edinburgh, using the process of nuclear transfer from a cell taken from a mammary gland. However, over time the sheep developed an incurable lung disease and was euthanised in 2003. Studies show that cloning is a feasible de-extinction approach for living species close to extinction because the resulting organism is identical. It requires intact living cells and is more suitable for species that exist and are not extinct yet.
Woolly mammoths (Mammuthus primigenius), which died around 10,000 years ago, might have some chance as scientists have discovered preserved scraps of their DNA found frozen in the Arctic tundra. However, using the cloning process would have limited results as the most intact mammoth samples have had little usable DNA because of their conditions of preservation. The second method would involve artificial insemination, in which the sperm of the mammoth will be put in an elephant egg cell. Elephants have the closest ancestry to the now-extinct mammoths. The resulting offspring would be a hybrid of the mammoth and its closest living relative in our world, the Asian elephant.
Colossal, which is the brainchild of Harvard geneticists George Church and Ben Lamm, will be introducing mammoth genes into the Asian elephant for conservation purposes. The organisation even declared in 2023 that it wants to have mammoth hybrid calves by 2028, and wants to reintroduce them to the Arctic tundra habitat. Research shows that after several generations of cross-breeding, these hybrids – an almost pure woolly mammoth could be produced.
However, studies show that this method could hinder the resurrection, as sperm cells of modern mammals can be potent for up to only 15 years after deep freezing. While the attempt sounds promising, the fact of the matter is none of the approaches described above will culminate in the birth of an organism that is an identical copy to one that is extinct. They will only be developing proxies and never the actual copy.
Another example is the Thylacine, also known as the Tasmanian tiger. They were widespread across Australia. These dog-like marsupials with stripes disappeared from the mainland around 2,000 years ago. Reports say they remained in Tasmania until the 1920s, when they were slaughtered by European colonisers who saw them as a threat to livestock.
Unfortunately, despite their DNA existing today, it is not completely whole. Scientists say that over time, exposure to UV light and the action of bacteria break down DNA into short fragments. As the sample gets older, smaller fragments are left behind, and eventually, there isn’t enough left. This is also one of the reasons why no one is trying to resurrect dinosaurs because their DNA is no longer present or relevant.
Another new technology is CRISPR-Cas9, which can replicate genes. Invented by Nobel Prize-winning scientists Emmanuelle Charpentier and Jennifer A Doudna in 2012, it is a revolutionary technology utilising a collection of genetic scissors derived from a bacterial defence mechanism. When facing a potential viral threat, these scissors copy and insert segments of the attacker’s DNA into their own genome, creating precision-cutting tools that exclusively target that specific genetic sequence. Its invention has transformed the speed and cost of editing genes, allowing scientists to accurately delete sections of DNA and create cuts where they can insert new genes.
Colossal Laboratories is using CRISPR to splice bits of mammoth DNA into the genome of the Asian elephant. The hybrid will be called a “mammophant”. However, limitations need to be overcome.
Cure for climate change
These mammophants would be placed in the cold Siberian tundra in the man-made Pleistocene Park, which will recreate the Pleistocene era in Siberia, and scientists believe they could help heal the ecology of the region – the void that mammoths left. Mammoths will stir up the icy surface of the landscape, stomp out the thick, low-oxygen trees, and expose healthy, carbon-trapping grasses. This can balance the greenhouse gases and help stop climate change.
While the resurrection of these extinct species becomes a reality by the day, questions are being raised on the cutting-edge science, ethical dilemmas, and ecological repercussions that surround this ambitious quest to bring back species long thought lost to the sands of time. The cure that scientists are visualising to save the climate through de-extinction has been looked at through a different lens. The environments these creatures once lived have changed drastically. Some of the plants that mammoths fed on are long gone. What is the probability of this new species surviving in the wild?
While for Tasmanian tigers, the environment would not be much of a problem as its habitat still exists in current-day Tasmania, these animals were at the top of the food chain. Bringing them back could mean changing the evolved food pyramid, threatening others’ coexistence.
Scientists who disagree with playing God argue that de-extinction happened for a reason, only the fittest survived. Science should focus on conserving species that are threatened today and help them sustain instead of resurrecting the gone ones.
De-extinction defined
De-extinction is the process of resurrecting species that have gone extinct, using scientific methods such as breeding, genetics, and reproductive cloning. Dolly the sheep was cloned in 1996 through somatic cell nuclear transfer (SCNT). The sheep gave many lambs, but developed severe health conditions and died in 2003.
Auroch and Quagga have a chance?
From the dodo, mammoth, and Tasmanian tiger, Colossal Biosciences has plans to do selective back-breeding to restore traits from the auroch, an extinct species of wild cattle. The Quagga Project in South Africa is using zebra DNA, attempting to breed the quagga, a subspecies that was hunted to extinction two centuries ago.
Short shot of success
In 2003, Spanish researchers achieved the cloning of the Iberian Pyrenean ibex, marking the first successful cloning of an extinct animal. The Centre for Research and Food Technology of Aragon used DNA extracted from the last living specimen, which had passed away three years earlier. Unfortunately, the cloned ibex’s life was short-lived, lasting only a few minutes before succumbing to a lung defect.