De-extinction (resurrection biology)
De-extinction, often referred to as resurrection biology, is the scientific endeavor aimed at bringing extinct species back to life. Although no extinct species have yet been successfully resurrected, researchers are making significant progress towards this goal. The process hinges on obtaining well-preserved DNA from extinct animals, which can sometimes be repaired using genetic editing tools like CRISPR. Cloning techniques are then employed to create viable offspring, with the Pyrenean ibex being the first notable attempt at de-extinction, albeit resulting in a short-lived individual.
Several species, including the woolly mammoth and the passenger pigeon, are being targeted for potential resurrection due to their close genetic relatives still existing today. However, the ethical implications of such actions are hotly debated; questions arise about the morality of resurrecting species and the possible impacts on current ecosystems. Critics argue that reintroducing extinct species may disrupt delicate ecological balances, drawing parallels to the adverse effects of invasive species. Despite these concerns, the field continues to explore the scientific possibilities of reversing extinction, focusing on the implications for biodiversity and the environment.
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De-extinction (resurrection biology)
De-extinction, or resurrection biology, is the study and process of returning extinct species to life. Although no extinct species have been successfully resurrected, scientists continue to make strides toward that goal. To return a species to life, scientists require adequately preserved DNA. They may also be able to repair damaged parts of an animal's genetic code with genetic editors like CRISPR. Once genetic material is secured, scientists use a number of cloning procedures to create a viable offspring.
Several extinct animals have been targeted for potential resurrection. Each animal became extinct while humans inhabited Earth, and each has close living genetic relatives. These animals include the woolly mammoth, the Pyrenean ibex, and the passenger pigeon. Many scientists and ethicists question if it is morally correct to restore extinct species to the world. Others question whether an extinct species would damage the local ecosystem in unexpected ways after being reintroduced into the environment.
Background
Some of the first attempts at resurrection biology utilized back breeding. Breeding backwards was an attempt to breed animals that looked like extinct species through selective breeding. Farmers and animal breeders utilized selective breeding to alter existing species.
Selective breeding involves breeding specific pairs of animals to encourage the prominence of particular physical or temperamental traits in their offspring. For example, dogs may be selectively bred to produce animals specialized for certain roles, such as herding or hunting.
In the early twentieth century, some cattle breeders tried to resurrect the aurochs, an ancient breed of extremely large cattle. The average aurochs was more than six feet tall, weighed more than a ton, and had a set of large horns. These cattle breeders paired cattle who shared these traits or who regularly produced offspring who shared these traits. Over the course of many generations, the offspring exhibited many of the characteristics of their aurochs ancestors. In the twenty-first century, Stichting Taurus, a Dutch foundation, started a program to breed the Tauros, a near-100-percent substitute for the extinct aurochs as part of the Rewilding Europe initiative.
Backward breeding has some severe limitations. While the resulting offspring may appear similar to the extinct animal, such as cattle that look much like ancient aurochs, they can never truly become that animal. However, modern scientific advancements have made true resurrection a possibility through cloning.
A clone is an organism with the same DNA as another organism. Clones exhibit extremely similar, though not always identical, physical characteristics. As scientists experimented with cloning, they managed to create several clones from embryonic DNA. However, embryonic DNA from extinct animals is usually unavailable, making that process useless for resurrection biology.
The first mammal cloned from cells harvested from an adult mammal was Dolly the sheep. Born in the Scotland on July 5, 1996, Dolly lived only six and a half years. However, her successful birth showed that cloning from samples harvested from an adult animal was possible.
Overview
Resurrection biology utilizes cloning to create a live animal of an otherwise extinct species. To accomplish this goal, biologists must first secure an intact set of DNA from an extinct species. Without living animals from which to harvest DNA, the biological material must be harvested from fossils or other well-preserved specimens.
Once DNA has been harvested, the scientists need an empty egg cell. In most cases, scientists use an egg cell from an animal similar to the extinct species. They use powerful tools to inject the extinct species' DNA into the egg cell, and then use a number of techniques to get the egg to undergo cell division. Once the cell begins to divide, they begin the process of in vitro fertilization. This involves artificially inseminating a similar animal with the reproducing egg cell of the extinct species, hoping that the live animal will give birth to a healthy, formerly extinct species. While this process has not yet been carried out successfully, scientists have come close on several occasions.
Other attempts at resurrection biology involve the application of CRISPR. CRISPR is a method scientists use to modify strands of DNA precisely. With the ability to modify DNA, scientists may not need to find intact DNA to recreate a species. Instead, they may be able to use similar traits from other species to fill in any missing or damaged sections of genetic code.
Many scientists are concerned with the ethical ramifications of resurrection biology. They question whether it is moral to bring back species that have gone extinct. Others theorize that the introduction of extinct species to an otherwise healthy ecosystem might damage the delicate ecological balance, causing harm to other species. To support this theory, scientists cite circumstances in which an invasive species has been introduced to an otherwise healthy environment. In some cases, these invasive species outperform native species in their ecological roles as they compete for resources, which leads to a reduction in the number of native species.
Despite ethical concerns, a number of species have become targets for scientists to resurrect. The Pyrenean ibex, which became extinct in 2000, is close genetic relatives with surviving goat species and has thus been the target of several cloning efforts. Experts believe that because the Pyrenean ibex is a close relative of the modern goat, it may be easier for a goat to carry an ibex embryo to full term. Although one such pregnancy was carried to term in the 2000s, the newborn ibex that was genetically identical to the donor ibex's cells died soon after birth due to a lung defect. Other efforts have been directed toward resurrecting the woolly mammoth. Scientists have relatively intact woolly mammoth DNA and believe that a modern elephant species may be able to carry a mammoth embryo.
The passenger pigeon has also been discussed as a potential candidate for resurrection biology. Unlike many other animal species, the passenger pigeon went extinct as a direct result of humans modifying their environment. Some scientists believe that humanity has a moral obligation to restore any species that people caused to go extinct. Like the woolly mammoth and the Pyrenean ibex, the passenger pigeon has close living relatives, making it a potentially viable candidate for cloning.
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