Scientifically speaking | Should we bring back woolly mammoths?

Recently, media attention has focused on “de-extinction” efforts to bring back extinct woolly mammoths. Meanwhile, elephants, their closest living relatives, are under threat in their natural habitats.

Humans have influenced the evolution of plants and animals with which we have been in contact throughout our existence. The horn size of bighorn sheep in Canada has dropped by 20% due to hunting. Many fish have also declined in size due to overfishing.

In Mozambique, the African elephant hunt for ivory to finance a long civil war has resulted in their populations declining by more than 90%. Research by biologist Shane Campbell-Staton and his colleagues at Princeton University published in Science on October 21 found that hunting elephants for their tusks resulted in them having no tusks left.

Most African elephants have tusks. Before the 15-year conflict, less than 20% of female elephants were defenseless. Today, poaching for ivory has left more than half of female elephants without tusks. And it’s not just that tusked elephants are being hunted to death and there are fewer around. The defenseless trait is selected from surviving elephants and is passed on to offspring which are also defenseless.

Researchers have found that the defenseless trait is caused by a mutation on the X chromosome. It is fatal in male elephants but gives birth to defenseless female elephants.

By comparing the genomes of defenseless and defenseless elephants, Campbell-Staton and his team were able to identify two candidate genes that are likely involved in the formation of tusks. Interestingly, these genes have equivalent versions in humans that are responsible for our incisors.

What is also concerning is that these changes in appearance due to poaching are not genetically encoded. In other words, even if conservation efforts are successful in increasing the numbers of African elephants, it will take time for the proportion of tusked elephants to increase.

Poaching is a serious threat to large animals such as elephants and tigers which are prized for their tusks and skins. These animals are also threatened by habitat loss due to human encroachment and the climate crisis.

Elephants are a key species. Female elephants without tusks eat different plants than elephants with tusks. Thus, the change in elephant populations will also have long-term consequences for the entire ecosystem.

I can’t help but think of the loss of elephants with tusks in the context of last month’s fanfare over a start-up reported trying to bring back woolly mammoths.

With the thaw of the Arctic, many well-preserved mammoths are unearthed from the ice. But even with these samples, DNA that is fragile is degraded and cannot be extracted intact. Scientists used DNA fragments to reconstruct the genetic blueprint of extinct woolly mammoths.

But many reports of resuscitation of woolly mammoths are incorrect. There is a huge gulf between figuring out an animal’s DNA sequence and recreating it. What this startup plans to do is use relatively new gene editing tools to insert genes from a woolly mammoth into its closest living relative, the Asian elephant.

This genetically modified elephant-mammoth hybrid will be implanted into a female elephant surrogate, which will give birth to offspring with certain mammoth cold adaptation genes. But since there are roughly 1.4 million differences in the genomes of Asian elephants and mammoths, the modified animals that will be created will not be mammoths. They will always be elephants.

The objective of the project is to “rewild” a modern ecosystem, the Siberian tundra, with these elephants adapted to the cold. There is some evidence that reintroducing large herbivores such as mammoths or elephants to the tundra might be good for restoring the environment, but no one has tried an experiment on this scale yet. The last woolly mammoth died about 4,000 years ago.

The state of health of genetically modified elephants with mammoth genes, their adaptation to their new environment and the long-term prospects of the project are not very clear. The number of cold-adapted elephants that will need to be created to support a population and the size of habitat needed are also debated.

Earth has suffered five previous mass extinctions. In the Anthropocene, we are currently in the middle of the sixth. A 2019 United Nations report estimated that humans are pushing a million species to extinction. We cannot save them all. Who decides which are candidates for extinction?

In a research article published in Nature on October 20, zoologist Yucheng Wang of the University of Cambridge and his colleagues found that the main culprit in the disappearance of the woolly mammoth was the rapid climate crisis that had caused their sources to dwindle. of food. Can we guarantee that the mammoth-like elephants that are introduced do not die quickly due to the current crisis?

To be clear, I’m not against de-extinction, but there should be some well-defined goals. De-extinction should not create a moral hazard problem providing an inconsequential excuse to continue destroying habitats and warming the planet. The main objective should be to save the species which currently exist or which have disappeared in recent years. These species should only be introduced after a solid public debate. Candidate species could include the Bali tiger or the northern white rhino.

The crux of the matter is this. For every species to exist on the planet, there must be an enabling environment. The goal of de-extinction should not be to create a jurassic park zoo type, but to reintroduce an organism that has a real chance of thriving in a sustainable habitat. If such a habitat does not exist, we will only briefly introduce species that become extinct again.

Trained microbiologist Anirban Mahapatra is the author of COVID-19: Separating Fact from Fiction

Opinions expressed are personal

About Alma Ackerman

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