The resurrection of extinct species is no longer something you just see in the movies. Cloning extinct species has been made possible through resurrection biology or species revivalism. Scientists have been able to clone sheep, cattle, goats, pigs and mice.The term “cloning” applies to a process more technically known as somatic cell nuclear transfer. Or, in other words, the DNA from the cell of an adult animal is inserted into another egg cell, working like a surrogate. But how does cloning work with extinct species?
Cloning extinct animals is a very controversial topic, bringing both positives and negatives. Even experts are unsure how they feel about it. “Resurrecting extinct animals is both “exhilarating and terrifying,” says Beth Shapiro, an expert in ancient DNA and a biologist at the University of California, Santa Cruz. In the near future will we see a wooly mammoth, passenger pigeon, and neanderthal walk the earth? More importantly, should we?
Whole species go extinct for many reasons. Weather, habitat loss, environmental toxins, disease, and shrinking population dynamics all contribute to extinction… But the main factor is humans. They contribute to overharvesting, overhunting, pollution, habitat destruction, and at times become a species’ main predators and food competitor. A single species’ disappearance can make a huge difference. Would cloning help environmental communities or would it be detrimental on a large scale?
You can’t simply clone a passenger pigeon, because they no longer have a fully intact set of chromosomes. But there is another possibility. Using fragments of the passenger pigeon DNA, scientists could synthesize the genes for certain traits and connect the genes into a rock pigeon. The cells containing the passenger pigeon DNA could be transformed into cells that produce eggs and sperm, which could be injected into rock pigeon eggs. (National Geographic) The hatched pigeons would be considered “rock pigeons” but the newborn pigeons would resemble passenger pigeons. Scientists could then breed these birds and select for specific traits, resulting in the offspring appearing like the passenger pigeon.
Some scientists do not want to stop at a pigeon. They want to go bigger — a lot bigger. They plan to revive the wooly mammoth, weighing in at six tons. This is not as far out of reach as it seems. In the Siberian tundra, well-preserved mammoths have been found including bone marrow, skin, hair, and fat. With these resources, if they find a living cell, it could be grown in a lab and manipulated to form an embryo. The embryo would then be implanted into an elephant, the closest relative of mammoth. And just like the passenger pigeon, it would be born from an elephant but the newborn would resemble a mammoth.
Even if researchers could clone a mammoth, passenger pigeon or any other extinct creature, it has to survive in the wild. This means having the right food and habitat; predators are also a concern to these new individuals in an ecosystem.
When it comes to science, there are always pros and cons — especially pertaining to reviving extinct species. Critics of de-extinction say reviving extinct animals would cause more harm to conservation efforts than good. Today, most species that are going extinct can be found in tropical forests. Says Stuart Pimm, a world leader in the study of present-day extinctions: “Saving a species through de-extinction when humans are burning forests and destroying native communities is a joke.”
Scientific and Medical Aspects of Human Reproductive Cloning Chapter 3: Animal Cloning
This book goes in depth to the origins of cloning and how far cloning has gone. In chapter 3 it states the specifics about cloning and answers many questions pertaining to cloning currently. The main question it answers: What is the state of science on cloning of animals? The author then breaks it up into subdivisions which goes more in depth, including several graphs and scientific findings.
A summary of their findings: In general, the efficiency of reproductive cloning in animals remains extremely low despite several years of experimentation. Animal cloning results in a wide variety of abnormalities, including greater than normal size (both during gestation and after birth), greater early- and late-gestation fetal morbidity and mortality, greater postnatal mortality, and various developmental defects in the immune, cardiovascular, and possibly nervous systems. In addition to the risks inherent in the overproduction of oocytes from egg donors, increased maternal morbidity and mortality are to be expected. The most likely reasons for the abnormalities are failures in reprogramming in the adult nucleus used for reproductive cloning, so that it fails to turn on all the appropriate embryo-specific genes at the right times, and errors in imprinting. Before human reproductive cloning is feasible, a great deal more research is necessary, including studies of cloning in nonhuman primates. Research focused on gaining an understanding of all aspects of reprogramming and imprinting, determining which steps in the reproductive cloning technique contribute to the overall low efficiency, and determining how these problems can be overcome would be most useful.