Recently, foreign media reported that geneticists at Harvard Medical School in the United States plan to "resurrect" the extinct mammoth. It's the kind of mammoth from Ice Age! The recently announced $15 million investment has been made a huge boost to plan to breed the first cubs within 4 to 6 years and send "resurrected" mammoth herds to the Arctic to help restore fragile Arctic tundra ecosystems, slow the melting of permafrost, and help humans fight climate change.
Mammoths, also known as longhairs, lived about 4.8 million to 10,000 years ago, are one of the largest mammals that have ever lived on land, and they are covered with thick long hairs that can withstand the cold, and are one of the typical symbols of the Ice Age. Probably due to climate change, overhunting by humans, etc., mammoths disappeared from the earth about 10,000 years ago.
<h1 class="pgc-h-arrow-right" data-track="496" > plan to resurrect mammoths</h1>
Regarding the "resurrection of mammoths", in fact, 10 years ago, it has been proposed by a Japanese scientific research team, who believe that mammoths can be bred through the cells of mammoths with the help of cloning technology.
Subsequently, experts found a well-preserved frozen mammoth corpse in the permafrost of Siberia, Russia, in 2012, and found living cells in the elephant's body. It should be known that cloning requires a complete structure of animal DNA, and DNA can be extracted from living cells. The discovery gave hopes of reviving mammoths skyrocketed. At the time, the Japanese team said it might be able to breed baby mammoths by the end of 2017.
However, now that it is 2021, mammoths have not been successfully "resurrected" by humans. What difficulties were encountered in this cloning process? Or is there another reason? Let's first understand how the mammoth was "resurrected".
After extracting the DNA from the mammoth remains, the scientists genetically sequenced the DNA of these cells and found that the genome of the mammoth is very similar to that of modern elephants. In particular, it is 99.6% similar to that of its close relatives, the DNA composition of Asian elephants. This means that mammoth cloning can be achieved through Asian elephants.
One of the ways to revive the mammoth is to first remove the nucleus from the modern elephant egg cell, then remove the nucleus of the mammoth living cell, and plant it in the denucleated egg cell of the modern elephant, and then prompt this new cell to divide and multiply into an embryo, and then implant it in the body of a modern mother elephant, surrogate it, and then clone a mammoth.
Although this idea seems beautiful, this technology still has a relatively large problem:
One is that it is difficult for xeno-oocytes to clone to support the development of cells of this species into an embryo; the other is the problem of xenotransfer transfer, the transfer of mammoth cloned embryos to close relatives for surrogacy, even if looking for the closest Asian elephant, the mother is bound to have some intractable immune rejection of the transferred embryo, resulting in the cloning embryo is difficult to develop in the Asian elephant. After all, the ancestors of mammoths and Asian elephants parted ways as early as 7.7-5.8 million years ago, and distant relatives separated by millions of years made cloning much more difficult.
But scientists' efforts and attempts to revive mammoths have never stopped. At present, there are still many different scientific teams working on mammoth resurrection plans, and their methods are different.
<h1 class="pgc-h-arrow-right" data-track="506" > a "false mammoth" edited by the gene</h1>
And the research team led by George Church, a geneticist at Harvard Medical School in the United States, plans to resurrect the mammoth?
Unlike the previous research direction of directly resurrecting mammoths by cloning, this time the research team plans to use CRISPR gene editing technology to splice DNA sequences extracted from well-preserved mammoth remains into the genome of Asian elephants, thereby cultivating a "mammoth-Asian hybrid" species. Because Asian elephants and mammoths are genetically similar, they will also have a high success rate.
They first screened the traits of mammoths, and then implanted the relevant genes into the genome of existing Asian elephants, and if they could be successfully bred, the new individuals they showed would be a new type of elephant with mammoth characteristics (thick subcutaneous fat, thick long hairs, and hardiness). They also hope to develop artificial uteruses that will allow "mammoth" embryos to give birth in artificial uteruses, which can also quickly breed large-scale mammoth colonies.
Although, the resurrected through this gene-editing technique is not a real mammoth. But now it is difficult to extract complete DNA from mammoth cells frozen in frozen soil, and the extracted DNA is either too fragmented or degraded and difficult to use, so the progress of directly resurrecting mammoths through cloning technology alone will be slower! In contrast, Professor Church's team's "mixed breed" research direction is much less difficult.
Professor Church said their goal is to create an elephant that can adapt to the alpine climate, can live in an environment of minus 40 ° C, and behave like a mammoth, and then release it to the Arctic, using the resurrected mammoth herd to restore the now moss-covered polar tundra to its original grassland ecology, thereby slowing the melting of the permafrost and the release of carbon in the Arctic.
If Professor Church's team's project comes to fruition, gene editing techniques could also be used to increase the genetic diversity of endangered populations and address the endangered extinction of species such as the Asian elephant.
<h1 class="pgc-h-arrow-right" data-track="516" > should we really resurrect mammoths? </h1>
While resurrecting mammoths may bring some benefits, mammoths are prehistoric creatures after all and have been extinct for thousands of years. If mammoths are really resurrected, under the influence of global warming, today's climate and ecological environment are no longer suitable for their survival. Even if they are placed in the Arctic, they may not be able to continue on Earth. For existing creatures in the Arctic, the resurrected mammoth is an invasive alien species, and it is not excluded that their introduction will adversely affect other local species, and even accelerate the extinction of local species!
From the perspective of natural biological evolution, the demise of ancient biological species such as mammoths is a natural process of biological evolution, and human beings should follow the laws of nature, and there is no need to resurrect ancient species that have become extinct. It is better to focus on maintaining biodiversity and helping to protect existing endangered species. What do you think?