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Mass Extinctions and Cloning: Should Humans Play God?
Habitat Loss and Species Extinction:
Of all the species to have lived on earth, Homo sapiens are the most successful. We have colonized all corners of the earth and have made our presence known to the most distant stars. Our highly evolved brains and a unique ability for oral and written language have helped us to conquer and control this small rock in space. Consider the amazing advances in the past ten thousand years, a mere eye blink in the eons of the cosmos. Metropolises dot the earth connected by six lane highways that snake their way through forests and under mountains. Businessmen commute cross country to scheduled meetings with their colleagues within a day. Indeed, they can even converse over the internet. Its not uncommon for the traditional family to own two cars, a refrigerator, a gas stove, a big screen TV, and a swimming pool. The luxuries of twenty-first century life are constantly growing. They are growing, however, at a deadly cost.
The rate of species extinction due to human expansion is rapidly increasing. Extinction is a natural process of biological systems. As dominant species move into new environments, their genes are favored over weaker populations. For billions of years, evolution has thinned out species less suited for this world, creating a biome with organisms highly adapted to their habitats. Today’s extinction rate, however, is not a natural phenomenon. According to the World Wildlife Foundation, experts have estimated the extinction rate to be 1,000-10,000 times what it would be if humans did not exist. The magnitude of this problem cannot be ignored.
Those who understand this crisis are doing their best to come up with a solution. It is well understood that habitat loss, whether caused by deforestation, urban sprawl, or pollution is the main cause of extinction. Clearly, a species needs a home and abundant resources to remain extant. Therefore, conservation biologists assist these at risk species by breeding them in captivity. It is natural to feel responsible for the hardships of these organisms. These technique, however, do not always work for endangered species. There is a reason why certain animals and plants were domesticated thousands of years ago while others were left in the wild.
Indeed, the ability to breed in captivity was essential to maintaining a domesticated population. Endangered species, such as migratory birds or fish, do not breed easily while in captivity. Moreover, if breeding is successful, many organisms need parental guidance during development to assure proper behavior in a natural environment. Another problem that may be overlooked is the possibility of the endangered species’ habitat being destroyed while they are being bred in captivity. Once the captive population was stabilized, the biologists would have no place to reintroduce them. Habitat loss, it would seem, is the main issue at hand here.
Cloning: A New Solution
Some scientists consider extinction an unavailable price of human advancement. Without any hope of preserving these pristine habitats and their associated biodiversity, conservation biologists are now collaborating with geneticists and bioengineers in hopes of reversing the process.
Recently in science news, scientists engineered embryos of the extinct Australian gastric brooding frog, Rheobatrachus silus, using a new cloning technique, somatic cell nuclear transfer (SCNF). In SCNF, the nucleus of an egg cell is removed and replaced by the nucleus of a somatic, or body, cell. Egg cells naturally have half the amount of DNA as somatic cells and thus need to be fertilized by sperm to reach the correct amount of DNA necessary for mitotic division. SCNF, however, allows egg cells to continue with mitotic division without fertilization. This technique is often used in stem cell research to study diseases. Customizable cells containing DNA related to a lethal disease can be created and further studied to understand the disease in question.
Australian researchers had preserved tissue from R. Silus dating back to the 1970s, before it went extinct. Using a de-nucleated egg from a related frog species as well as the nucleus from the preserved tissue, these scientists were able to create embryos of a frog that had gone extinct in 1983. This is a new technology, ergo it was not surprising to find that the embryos had died after a few days. Nevertheless, it was a fascinating discovery and one that set the ground for future research into this field.
Extinction to Invasiveness:
For some conservationists, this new and emerging science may seem like the solution to mass extinction in the twenty-first century. We should consider the possible consequences, however, before embarking on a massive “de-extinction” excursion. The rate of extinction is saddening; however, it must be understood that these species went extinct for a reason: there is no more room for them on this planet. Each species in an ecosystem has a niche, or a certain role it plays in the system. When a species goes extinct, that role is taken over by another species, or it disappears completely. Thus, if we were to repopulate the world with previously extinct species, they would be placed in ecosystems that no longer have room for them, especially if they went extinct 30 years ago. The use of this technology for “de-extinction” is unethical and could result in the destruction of even more habitats.
Amphibians are being wiped out right and left as anthropogenic toxins get absorbed into their skin. Their natural habitats are polluted with runoff from our industrial factories. Even if we were to successfully clone a population of gastric brooding frogs, where would we put them? If their habitats are destroyed, they would have to be introduced into a habitat where other amphibians, unaccustomed to this frog, are already living. The question then arises: are we repopulating the earth with its natural inhabitants or are we just increasing the amount of invasive species?
Invasive species lead to the extinction of native species in the same way as habitat destruction. In some sense, invasive species do destroy habitats by changing their composition. This can be seen clearly on the Galápagos Islands, where invasive species have increasingly become a problem as tourism increases. Before humans colonized the islands in the nineteenth century, the Galápagos were a pristine environment with some of the highest rates of endemism in the world. The organisms of Darwin’s natural laboratory evolved alone, separated from outside populations. Consequentially, the adaptations these organisms display resulted from isolation.
In the same way that Native Americans were unaccustomed to European diseases during the colonial period, the Galápagos endemics were in no shape to challenge mainland species being brought over from South America. Canine and feline derived infections began to devastate sea lion populations of the four islands colonized by humans. The slow moving tortoises of Isabela Island were practically wiped out by feral goats, resulting in a conservation plan to eliminate all the goats on Isabela using machine gun mounted helicopters. The Galápagos is an excellent laboratory for viewing the effects of introduced species on present populations of native species.
Somatic cell nuclear transfer is an ingenious discovery. It will be used in medical research to help solve the mystery of numerous genetic diseases. It should not, however, be used to bring back species that have already left the pool of biodiversity. It is an unethical procedure and one that could have drastic effects for those species still persevering through human destruction. The only true way to slow the anthropogenic extinction of species is to stop destroying habitats. We must preserve the pristine environments and biodiversity we still have. “The one process ongoing in the 1980s that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats,” E.O. Wilson observed. He was exactly right. We are perpetrating an atrocity on the world’s diversity; however, the damage must be repaired slowly. It cannot and should not be repaired over night with one laboratory procedure. The mistakes we have made in past few centuries can only be righted by pressuring those few in charge. Uniting conservation minded people from all over the world is the only way in which policies affecting habitat loss can be amended.
Smith, D. 2013. Lost Frog DNA revived: Lazarus Project. University of New South Wales. Press Release